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| 3086 | Optimization of glucose infusion protocol for glucoCEST imaging | |
| Anina Seidemo1, Patrick M. Lehmann1, Anna Rydhög2, Ronnie Wirestam1, Xiang Xu3,4, Akansha A. Sehgal3,4, Yi Zhang5, Frederik Testud6, Pia C. Sundgren7,8, Peter C.M. van Zijl3,4, and Linda Knutsson1,3 | ||
1Department of Medical Radiation Physics, Lund University, Lund, Sweden, 2Centre for Medical Imaging and Physiology, Skåne University Hospital, Lund and Malmö, Sweden, 3Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 4F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, 5College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China, 6Siemens Healthcare AB, Malmö, Sweden, 7Department of Diagnostic Radiology, Lund University, Lund, Sweden, 8Lund University Bioimaging Center, Lund University, Lund, Sweden |
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The intravenous glucose injection used in dynamic glucose-enhanced (DGE) imaging is related to transient sensations which can be unpleasant for the subject and may cause movements. We have investigated the effect of different infusion durations in terms of sensational side effects and with respect to the relation between arterial DGE signal and venous blood glucose levels. Our findings indicate that the DGE image quality does not benefit from a fast glucose injection and we conclude that a slower infusion should be used to increase patient comfort and reduce the risk for patient motion related to the glucose injection. |
| 3087 | Application of GluCEST imaging in mapping cingulate cortex of Nicotine dependence subjects at 7.0T | |
| Ravi Prakash Reddy Nanga1, Emily Devlin1, Claudia Ianelli2, Deepa Thakuri1, Dushyant Kumar1, Hari Hariharan1, James Loughead1, Cynthia Neill Epperson2, and Ravinder Reddy1 | ||
1Perelman School of Medicine at The University of Pennsylvania, Philadelphia, PA, United States, 2University of Colorado School of Medicine, Aurora, CO, United States |
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Nicotine addiction is still one of the most preventable causes of chronic illness and premature death, and cessation regardless of age has positive effects on health outcomes (WHO, 2015). As such, there is growing interest in developing novel therapies and diagnostic aids to treat and monitor the nicotine addiction across the lifespan. Glutamate weighted chemical exchange saturation transfer (GluCEST) imaging was used to spatially map the glutamate levels of dorsal anterior cingulate cortex (dACC). We observed lower GluCEST contrast in females in the dACC regardless of smoking status. No significant difference in GluCEST was observed between the smokers and non-smokers. |
| 3088 | Volumetric CEST May Provide Insight into Clinical Neuroprotection Stratification in Sub-Acute Ischaemic Stroke | |
| Alex K Smith1, Davide Carone2, James Garrard2, Michael A Chappell1,3, Peter Jezzard1, and James Kennedy2 | ||
1Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom, 2Acute Vascular Imaging Centre, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom, 3Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom |
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Understanding the contributions of secondary injury following ischaemic stroke is critical for developing post-stroke neuroprotective strategies. Nuclear Overhauser effect (NOE) CEST and MT are techniques sensitive to aliphatic compounds and macromolecules, respectively, and which may point to intracellular microstructural integrity post-ischaemia, potentially helping stratification of patients for further treatment. We show that rapid 3D volumetric measurements at clinical MRI strength in patients demonstrate significant reductions in relative NOE ratio and MT exchange rate, both within conventionally defined areas of infarction using ADC, and in areas in which ADC is insensitive (infarct growth). Further work is required to confirm this observation. |
| 3089 | Real-time motion and retrospective receiver sensitivity correction for gluCEST using volumetric navigators (vNavs) at 7T | |
| Esau Poblador Rodriguez1, Philipp Moser1, Sami Auno2, Korvinian Eckstein1, Stephan Gruber1, Benjamin Schmitt3, Andre van de Kouwe4, Siegfried Trattnig 1, and Wolfgang Bogner1 | ||
1High Field MR Centre, Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria, 2Department of Physics, University of Helsinky, Helsinki, Finland, 3Siemens Healthineers, Sydney, Australia, 4Harvard Medical School, Boston, MA, United States |
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CEST is susceptible to subject motion not only due to misregistration of MR images acquired over time and subsequent alterations of B0 field, but also due to the related receiver sensitivity (B1-) inhomogeneities. We propose to correct for ∆B1- from the images generated by an interleaved EPI navigator used for prospective motion correction. We show the benefit of the proposed method, in combination with B1+ and dynamic B0 corrections, to restore a glutamate weighted CEST map in an active healthy volunteer. |
| 3090 | On the feasibility of a single scan B1+ correction scheme in combination with Multiple Interleaved Mode Saturation for quantitative CEST at 7 Tesla | |
| Andrzej Liebert1, Katharina Tkotz1, Juergen Herrler2, Patrick Liebig3, Rene Gumbrecht3, Arnd Doerfler2, Frederik B. Laun1, Michael Uder1, Moritz Zaiss2,4, and Armin M. Nagel1,5 | ||
1Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, 2Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, 3Siemens Healthcare GmbH, Erlangen, Germany, 4Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, 5Institute of Medical Physics, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany |
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In Chemical Exchange Saturation Transfer MR both B1+-inhomogeneity correction and mitigation have their limitations, in particular if large field-of views shall be covered. To overcome these limitations a Multiple Interleaved Mode Saturation scheme was applied together with a linear B1+ inhomogeneity correction method. Repeatability and reproducibility of the MTRRex metric for rNOE and APT were investigated. A combination of MIMOSA and a simple single point correction allows achieving repeatable and reproducible CEST contrast in whole brain with an acquisition time of 4min 54s. |
| 3091 | Ultrafast 3D Steady-State Chemical Exchange Saturation Transfer (CEST) MRI with Incoherent Sampling at 7T | |
| Sugil Kim1, HoonJae Lee2, and Seong-Gi Kim2,3 | ||
1Siemens healthineers Ltd, Seoul, Republic of Korea, 2Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea, 3. Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea |
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CEST MRI exploits saturation transfer-induced proton exchange and its corresponding, indirect loss of water signal, has been shown to provide a novel contrast mechanism in MRI. However, CEST MRI is prone to B0 inhomogeneities. To resolve this problem, CEST MRI requires multiple-acquisition. To acquire z-spectrum of whole brain at ultrahigh field of 7T, there are multiple issues to be tackled; a prohibitively long acquisition time, potential high power deposition, and B0 drift during a long scanning time. In this work, we proposed the rapid steady-state CEST MRI pulse sequence incorporating with incoherent sampling in 3D segmented EPI at 7T |
| 3092 | Investigation of a parallel transmission (pTx) GRE-readout with customized pulses for CEST MRI at 7 Tesla | |
| Katharina Tkotz1, Andrzej Liebert1, Jürgen Herrler2, Patrick Liebig3, Arnd Dörfler2, Michael Uder1, Moritz Zaiss2,4, and Armin M. Nagel1,5 | ||
1Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, 2Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, 3Siemens Healthcare GmbH, Erlangen, Germany, 4Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, 5Institute of Medical Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany |
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In Chemical Exchange Saturation Transfer MRI B1+-inhomogeneity influences both saturation and acquisition of the signal. Typically only a correction of the inhomogeneity of the CEST saturation is performed while the inhomogeneity of the readout is neglected. The influence of the readout was investigated in measurements using standard inhomogeneous 1Tx readout and a homogenized readout with customized pTx pulses. Compared to the 1Tx readout the readout with pTx pulses shows an increase of the homogeneity of the CEST contrast for CEST agents with low SNR like the amides and in regions with low 1Tx flip angle like the cerebellum. |
| 3093 | Protein-sensitive CEST-MRI of Alzheimer’s patients at 3 T | |
| Steffen Goerke1, Johannes Breitling1, Katharina M. Kubera2, Moritz Zaiss3, Dusan Hirjak4, Robert C. Wolf2, Anoshirwan A. Tavakoli5, Heinz-Peter Schlemmer5, Daniel Paech5, Mark E. Ladd1, and Peter Bachert1 | ||
1Divsion of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Center for Psychosocial Medicine, Department of General Psychiatry, Heidelberg University, Heidelberg, Germany, 3Neuroradiology, University of Erlangen-Nürnberg, Erlangen, Germany, 4Departement of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany, 5Departement of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany |
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In this study, the potential of CEST-MRI as a tool for diagnostic imaging of Alzheimer’s patients was evaluated. Although the study size was yet too small to draw final conclusions, a significant decrease of the rNOE-CEST signal in Alzheimer’s patients was observed. This finding was in line with previous in vitro studies on the monitoring of protein aggregation using CEST-MRI. A diagnostic tool for Alzheimer’s based on CEST-MRI would allow avoiding invasive examinations and thus more frequent follow-ups allowing an improved level of patient care. |
| 3094 | Investigation of Optimizing Chemical Exchange Saturation Transfer Imaging for Tuberous Sclerosis Epilepsy at 3 Tesla | |
| Qingqing Wen1, Kang Wang2, Yi-Cheng Hsu3, Yi Sun3, Dan Wu1,2, and Yi Zhang1,2 | ||
1Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China, 2Department of Neurology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China, 3Siemens Healthcare Ltd., Shanghai, China |
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Epilepsy is a prevalent neurological manifestation of Tuberous Sclerosis Complex (TSC). Here, the feasibility of applying Chemical Exchange Saturation Transfer (CEST) imaging to TSC epilepsy is investigated, with the radio-frequency saturation power, duration and frequency offsets optimized. The maximum CEST contrast between cortical tubers and normal white matter was achieved for an optimal saturation duration of 1000ms, while the optimal saturation frequency offset was related to the saturation power. Importantly, distinct contrast between tubers and normal white matter was demonstrated for TSC epilepsy for the first time, indicating CEST may serve as a potentially useful tool for diagnosing TSC. |
| 3095 | Frequency-stabilized chemical exchange saturation transfer imaging with free induction decay readout | |
| Ruibin Liu1, Hongxi Zhang2, Yi-Cheng Hsu3, Caixia Fu4, Yi Sun3, Dan Wu1, and Yi Zhang1 | ||
1Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China, 2Department of Radiology, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China, 3MR Collaboration, Siemens Healthcare Ltd., Shanghai, China, 4Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China |
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CEST imaging is highly sensitive to temporal B0 drift, for which a frequency-stabilized CEST (FS-CEST) sequence was recently proposed by inserting a frequency stabilization module in front of the conventional non-frequency-stabilized CEST (NFS-CEST) sequence. Here, the frequency stabilization module in the FS-CEST sequence was further simplified by replacing the original gradient-echo readout with free induction decay (FID) readout. The proposed FS-CEST sequence with FID readout in the frequency stabilization module was validated in phantoms on a 3T Siemens Prisma scanner and in 15 volunteers on a 3T Philips Achieva scanner, both leading to improved CEST maps. |
| 3096 | Snapshot whole brain CEST MRI at 3T with 3D-EPI | |
| Sebastian Mueller1, Rüdiger Stirnberg2, Suzan Akbey2, Philipp Ehses2, Klaus Scheffler1,3, Tony Stöcker2,4, and Moritz Zaiss1,5 | ||
1High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, 2German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, 3Department of Biomedical Magnetic Resonance, Eberhard Karls University Tuebingen, Tuebingen, Germany, 4Department of Physics and Astronomy, University of Bonn, Bonn, Germany, 5Department of Neuroradiology, University Hospital Erlangen, Erlangen, Germany |
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CEST MRI provides metabolite-based contrasts but often suffers from poor volume coverage or spatial resolution. We optimized and included a snapshot 3D-EPI readout and propose a suitable post-processing pipeline to generate CEST contrast in the whole brain at clinical B0=3T. It is shown that CEST MRI with 1.8mm isotropic nominal resolution at a field of view of 256x224x156mm³ is feasible within 4.3s per presaturation frequency offset. The approach is adaptable for any presaturation scheme. Exemplarily low power saturation was performed and fitted Lorentzian amplitudes gave a coefficient of variation <8.5% across three healthy subjects. |
| 3097 | Glioma staging with CEST asymmetry curves and amides/amines ratio. | |
| Laura Mancini1,2, Stefano Casagranda3, Francisco Torrealdea4, Marilena Rega4, Enrico De Vita1,5, Bruno Lopez3, Sebastian Brandner6,7, Benjamin Schmitt8, Patrick Liebig8, Eser Sanverdi1, Xavier Golay1,2, and Sotirios Bisdas1,2 | ||
1Lysholm Dept of Neuroradiology, National Hospital for Neurology & Neurosurgery, UCL Hospitals NHS Foundation Trust, London, United Kingdom, 2UCL Institute of Neurology, London, United Kingdom, 3Olea Medical, La Ciotat, France, 4University College of London Hospitals NHS Foundation Trust, London, United Kingdom, 5Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, 6Department of Neurodegenerative Disease, Institute of Neurology UCL, London, United Kingdom, 7National Hospital for Neurology & Neurosurgery, UCL Hospitals NHS Foundation Trust, London, United Kingdom, 8Siemens Healthcare Limited, Erlangen, Germany |
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Gliomas are the most common primary brain tumour, whose staging depends on the IDH and 1p/19q status and is reflected in different prognoses and clincal management. CEST is a highly sensitive MRI technique detecting amide- and amine-containing mobile proteins. The CEST amides/amines ratio has been proposed as a measure of pH in stroke. We show that CEST amides/amines ratio is much more sensitive than separate amides and amines CEST in differentiating gliomas with the best prognosis (IDH-mutant_1p/19q-retained) from those with the worst prognosis (IDH-wildtype). The different shapes in CEST asymmetry spectra could also potentially help in glioma staging. |
| 3098 | AutoCEST: a Machine-Learning Approach for Optimal CEST-MRI Experiment Design and Quantitative Mapping | |
| Or Perlman1, Bo Zhu1,2, Moritz Zaiss3,4, Matthew S. Rosen1,2, and Christian T. Farrar1 | ||
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States, 2Department of Physics, Harvard University, Cambridge, MA, United States, 3Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 4Department of Neuroradiology, University Clinic Erlangen, Erlangen, Germany |
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The most common metric for CEST analysis is the magnetization-transfer-ratio asymmetry. Although qualitatively useful, it is affected by a mixed contribution from several exchange properties and requires experiment-specific protocol optimization. Herein, we propose a machine-learning framework for simultaneously tackling two challenging tasks: (1) automatic design of the optimal CEST acquisition schedule; (2) automatic extraction of fully quantitative CEST maps from the acquired data. The method was evaluated in simulations and phantoms at 4.7T. The resulting data acquisition and reconstruction times were 52 s and 36 ms respectively, providing quantitative exchange-rate and volume fraction maps with good agreement to ground-truth. |
| 3099 | Two-stage denoising of CEST MRI data by principal component analysis of spectral groups | |
| Johannes Breitling1, Steffen Goerke1, Mark E. Ladd1, Peter Bachert1, and Andreas Korzowski1 | ||
1German Cancer Research Center (DKFZ), Heidelberg, Germany |
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In this study a novel method for the denoising of CEST MRI data is presented, combining the formation of subsets of similar spectra and the subsequent application of a principal component analysis. Exploiting only the subtle spectral differences of these reduced datasets – as opposed to using all spectra for the analysis – allows for a better identification and isolation of the obscured underlying spectral features. The proposed denoising resulted in an SNR gain by approximately a factor of four compared to the noisy initial data and an additional 14% compared to the conventional principal component analysis denoising. |
| 3100 | Deep Learning Reconstruction improves CEST MRI | |
| Shu Zhang1, Xinzeng Wang2, F. William Schuler1, R. Marc Lebel3, Mitsuharu Miyoshi4, Ersin Bayram2, Elena Vinogradov5, Jason M. Johnson6, Jingfei Ma7, and Mark D. Pagel1 | ||
1Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 2Global MR Applications & Workflow, GE Healthcare, Houston, TX, United States, 3Global MR Applications & Workflow, GE Healthcare, Calgary, AB, Canada, 4Global MR Applications & Workflow, GE Healthcare Japan, Tokyo, Japan, 5Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 6Neuroradiology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 7Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States |
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Image reconstruction using deep learning (DL Recon) is capable of enhancing image signal-to-noise ratio (SNR) without losing image resolution or altering the image contrast. Our study demonstrates that CEST imaging and quantification, which are often limited by SNR and long scan time, can be improved with DL Recon. Our results clearly indicated that DL Recon can be used for CEST imaging with higher spatial resolution without or with only a mild increase in scan time or for CEST imaging in reduced scan time by using parallel imaging without the typical SNR penalty. |
| 3101 | Deep learning-based B0 inhomogeneities mapping using sparse CEST spectral data | |
| Yiran Li1, Danfeng Xie1, Hanlu Yang1, Li Bai1, Guanshu Liu2, and Ze Wang3 | ||
1Department of Electrical and Computer Engineering, Temple University, PHILADELPHIA, PA, United States, 2Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 3Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, United States |
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Chemical Exchange Saturation Transfer (CEST) is an MR based imaging method that can image compounds containing protons exhibiting a suitable exchange rate with bulk water. One of the crucial technical hurdles in CEST MRI is, as CEST signal highly depends on the saturation frequency, how to accurately correct the B0 inhomogeneity in each voxel. We proposed two deep learning (DL) based methods for estimating B0 inhomogeneities to accelerate CEST imaging using spare samples. While only a small sample size was used, our study shows the potential of DL-based B0 mapping, which can greatly reduce the total CEST acquisition time. |
| 3102 | In vivo proton exchange rate MRI of stroke patients | |
| Zhenxiong Wang1,2, Mehran Shaghaghi2, Yiran Zhou1, Wenzhen Zhu1, and Kejia Cai2 | ||
1Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China, 2Departments of Radiology, Department of Bioengineering, and the Center for MR Research, University of Illinois at Chicago, Chicago, IL, USA, Chicago, IL, United States |
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In this study, we demonstrated that in vivo proton exchange rate MRI based on improved omega plot can serve as a novel and independent MRI contrast for assessing ischemic brain tissues of stroke patients. |
| 3103 | To Evaluate Effect of Interpolation Methods for B0 inhomogeneity correction on computation of CEST MRI Contrast in Human Brain at 3T and 7T | |
| Anup Singh1,2, Ayan Debnath1,3, Rakesh Kumar Gupta4, and Ravinder Reddy3 | ||
1Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India, 2Biomedical Engineering, AIIMS, New Delhi, India, 3Radiology, University of Pennsylvania, Philadelphia, PA, United States, 4Radiology, Fortis Memorial Research Institute, Gurugram, India |
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CEST MRI provides high resolution mapping of molecules such as Glutamate, Creatine, labile proteins/peptide, etc. CEST MRI contrast computation using asymmetry analysis require interpolation of data at different frequency offsets for B0 inhomogeneity corrections. In this study, different interpolation methods such as polynomial, cubic, spline and smoothingspline were compared for B0 inhomogeneity correction of various CEST contrasts(GluCEST-w, APT-w, CrCEST-w) at different field strength (3T, 7T). The 2nd and 3rd degree polynomial interpolations provided better B0 inhomogeneity correction for in vivo data from human brain. Polynomial interpolations for APT-w also improved differentiation of high-grade-glioma and low-grade-glioma tumors at 3T. |
| 3104 | Post-acquisition correction of the T1 relaxation effect for fast multi-slice CEST MRI | |
| Tao Jin1 | ||
1University of Pittsburgh, Pittsburgh, PA, United States |
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Rapid multi-slice CEST MRI can be achieved by the immediate acquisition of multiple slices after a single irradiation pulse. However, the signals from the slices acquired after the 1st slice are contaminated by the T1-relaxation relaxation effect. In this work, we propose a simple post-acquisition correction method to compensate for the relaxation effect in the multi-slice CEST signals. |
| 3105 | Exchangeable Proton Spectroscopy using RACETE-FLEX | |
| Fabian Tobias Gutjahr1,2, Simon Mayer2, and Peter M Jakob2 | ||
1Comprehensive Heart Failure Center, University Hospital Wuerzburg, Wuerzburg, Germany, 2Experimental Physics 5, University Wuerzburg, Wuerzburg, Germany |
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RACETE-FLEX is a combination of the novel RACETE-method and the spectroscopic FLEX method. RACETE is a method for imaging chemical exchange with positive contrast with concurrent water suppression. Combining the RACETE approach with the FLEX frequency labeling strategy leads to a high sensitivity exchangeable proton spectroscopy method. |
| 3106 | Differentiation between Intra-Cranial Mass Lesions using Machine Learning approach on Amide Proton Transfer-weighted (APT-w) CEST MRI | |
| Ayan Debnath1, Manish Awasthi1, Neha Vats1, Rakesh Kumar Gupta2, and Anup Singh1,3 | ||
1Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India, 2Department of Radiology, 2Fortis Memorial Research Institute, Gurgaon, Haryana, India, 3Department of Biomedical Engineering, All India Institute of Medical Science, New Delhi, India |
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It is challenging to differentiate between intra-cranial mass lesions (ICMLs) due to similar appearance using conventional MRIs. Amide-proton-transfer-weighted(APT-w) MRI provides differentiation among ICMLs with lower sensitivity ad specificity. The accuracy of classification between neo-plastic mass lesions and infective mass lesions as well as differentiation between low-grade-glioma and high-grade-glioma improves by implementing machine learning classifier based on features from APT-w CEST MRI. An optimized support-vector-machine with 10-fold cross-validation and optimal set of features extracted using Random forest based feature selection provided high accuracy of around 90%. |
| 3107 | Significant changes of APT signal in the Substantia Nigra and striatum of subacute PD mouse induced by MPTP | |
| Quan Tao1, Peiwei Yi1, Zimeng Cai1, Yingjie Mei2, Zhifeng Chen1, Ruiyuan Liu1, Wufan Chen1, and Yanqiu Feng1 | ||
1School of Biomedical Engineering, Southern Medical University, Guangzhou, China, 2Philips healthcare, Guangzhou, China |
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Chemical exchange saturation transfer (CEST) MRI has been widely investigated for the early diagnosis of neurological diseases, such as brain tumor and neurodegenerative disorders. The goal of this study was to develop an imaging biomarker for the future intervention and treatment of PD in clinic. For such purpose, a novel radial-sampling steady-state CEST sequence based ultrashort echo time (UTE) readout was used to acquire the Z-spectrum in the mouse brain of subacute PD model induced by MPTP. |
| 3108 | Amide Proton Transfer imaging for differentiation of Tuberculomas from High-Grade Gliomas | |
| Karthik Kulanthaivelu1, Sanita Raju2, Jitender Saini1, Atchayaram Nalini2, Nishanth Sadashiva3, Shashank Hegde4, Narayana Krishna Rolla5, and Indrajit Saha5 | ||
1Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Bengaluru, India, 2Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India, 3Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bengaluru, India, 4Philips Healthcare, Bengaluru, India, 5Philips Health Systems, Philips India Ltd, Bengaluru, India |
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Amide proton transfer imaging was investigated for its potential to discriminate tuberculomas from high-grade gliomas. The diagnosis was confirmed by histopathology, CSF examination or response to anti-tubercular therapy. The MTRasym value of the Tuberculomas (mean 2.32± 0.50 s.d.) was significantly lower than high-grade gliomas (mean 4.32±0.84s.d.). Lower MTRasym values in tuberculomas are suggestive of relatively reduced mobile amide protons compared to the tumoral microenvironment. Perilesional elevated APT values in tuberculomas are a unique observation and may reflect a milieu of inflammation. |
| 3109 | Investigating the dependence of APT-CEST imaging in the human breast at 7 Tesla on the menstrual cycle | |
| Lisa Loi1, Ferdinand Zimmermann2, Andreas Korzowski2, Jan-Eric Meissner2, Johannes Breitling2, Peter Bachert2, Mark Edward Ladd2, Heinz-Peter Schlemmer1, Sarah Schott3, Sebastian Bickelhaupt4, Steffen Goerke2, and Daniel Paech1 | ||
1Radiology, German Cancer Research Center, Heidelberg, Germany, 2Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany, 3Gynecology, University Hospital Heidelberg, Heidelberg, Germany, 4German Cancer Research Center, Heidelberg, Germany |
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Compared to conventional dynamic contrast-enhanced MR-mammography, which is known to be significantly affected by the phase of the menstrual cycle, the menstrual cycle-related effect on APT CEST MRI in the human breast is still unknown. This is the first study investigating the influence of the menstrual cycle on APT CEST MRI in fibroglandular breast tissue of seven healthy premenopausal women. No significant signal intensity differences in fibroglandular breast tissue between the follicular and the luteal phase of the menstrual cycle were observed, which suggests that APT contrasts are comparable regardless of the phase of the menstrual cycle in premenopausal women. |
| 3110 | Relaxation-compensated APT CEST imaging in breast cancer diagnostics at 7T | |
| Lisa Loi1, Ferdinand Zimmermann2, Andreas Korzowski2, Jan-Eric Meissner2, Peter Bachert2, Mark Edward Ladd2, Heinz-Peter Schlemmer1, Sebastian Bickelhaupt3, Steffen Goerke2, Sarah Schott4, and Daniel Paech1 | ||
1Radiology, German Cancer Research Center, Heidelberg, Germany, 2Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany, 3German Cancer Research Center, Heidelberg, Germany, 4Gynecology, University Hospital Heidelberg, Heidelberg, Germany |
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Relaxation-compensated, fat-corrected and B1-corrected APT CEST MRI is a novel MR imaging technique that generates complementary information to conventional MR-mammography. In this study, the ability of this improved APT CEST metric was investigated in nine patients with newly diagnosed breast cancer. Compared to normal appearing fibroglandular breast tissue, significantly increased APT CEST signal intensities in breast cancer tissue were observed. Consequently, this MRI approach represents a contrast agent-free method that may enable a non-invasive differentiation of breast cancer and normal appearing breast tissue and, therefore, help to increase diagnostic accuracy in breast cancer imaging. |
| 3111 | Induced Saturation Transfer Recovery Steady State (iSTRESS) for proton exchange rate imaging with MRI | |
| Mehran Shaghaghi1 and Kejia Cai1,2,3 | ||
1Radiology, University of Illinois - Chicago, Chicago, IL, United States, 2Bioengineering, University of Illinois - Chicago, Chicago, IL, United States, 3Center for MR Research, University of Illinois - Chicago, Chicago, IL, United States |
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We present a novel method to induced saturation-transfer-recovery steady-states for determining proton exchange (kex) with low saturation power, short duration, and hence negligible SAR deposition. Our previous study has demonstrated that omega plotting with direct saturation (DS) signal removed can be used to map kex of healthy brains in vivo. However, omega plot, based on steady-state saturation assumption, requires long scanning time and potential high SAR deposition, which makes it non-applicable for clinical studies. Our suggested method, validated by simulations and phantom imaging, shows great promise for in vivo proton exchange rate imaging and clinical applications. |
| 3112 | Layer-dependent Transient Saturation Transfer MRI at 7T | |
| Catarina Rua1, Sanne Kaalund2, James B Rowe2,3, Christopher T Rodgers1, and Guy B Williams1 | ||
1Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom, 2Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom, 3Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, United Kingdom |
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The human cortical mantle has distinct non-uniform layers of gray matter. In this study we used ultra high-resolution MT-weighted imaging at 7T with varying mixing times to measure the transient effects of the magnetization suppression through the primary visual cortex (V1). The MT effect was monitored across different cortical depths to evaluate the effect of the macromolecular pool (MP) and myelination. |
| 3113 | Disparity between Glucose Exchange and Osmolality in Pathological Tissue using Dynamic Glucose Enhanced Magnetic Resonance Imaging (DGE-MRI) | |
| Julius Juhyun Chung1, Geun Ho Im2, Jung Hee Lee2,3, Tao Jin1, and Seong-Gi Kim2 | ||
1Radiology, University of Pittsburgh, Pittsburgh, PA, United States, 2Center for Neuroscience Imaging Research, Suwon, Republic of Korea, 3Radiology, Samsung Medical Center, Seoul, Republic of Korea |
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CEST has been used as a way to monitor glucose transport as a way of studying uptake as well as permeability. However, signal is not solely affected by exchange but also osmolality shifts with significant intravenous dosage. Using MCAO, we study disparity between these two effects and how they may lead to obfuscate signal sources. With the injection of glucose after the onset of ischemia, +1.2 ppm , -1.2 ppm, and MTR asymmetry curves behave quite differently. Both sides of the spectrum must be scrutinized to have a better picture of what is going on during glucose dosage. |
| 3114 | Glucose Metabolism by Dynamical Glucose Enhanced imaging | |
| Yu-Wen Chen1 and Dennis Wenhan Hwang2 | ||
1, IBMS N123, Academia Sinica, Taipei, Taiwan, 2IBMS, Academia Sinica, Taipei, Taiwan |
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Dynamic glucose-enhanced (DGE) images, detected by CEST, was used to provide direct information on glucose metabolism. It also provides the spatial distribution of the metabolic processes. The time-dependent glucose concentration variation in the striatum of HD shows that the glucose uptake in the HD mice striatum decreases with age. The groups of older than 9-11 weeks HD mice were easy to find the symptoms of HD, and their glucose uptaking also show a significant decrement. By contrast, WT mice show a mild decrease in the glucose uptake for the mice with similar age. |
| 3115 | Dynamic glucose-enhanced (DGE) MRI for brain tumors: a small-scale clinical observational study | |
| Jianhua Mo1, Xiang Xu2,3, Xianglong Wang1, Linda Knutsson2,4, Akansha A Sehgal2,3, Peter C. M. van Zijl2,3, and Zhibo Wen1 | ||
1Zhujiang Hospital, Southern Medical University, Guangzhou, China, 2Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 3F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, United States, 4Department of Medical Radiation Physics, Lund University, Lund, Sweden |
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Dynamic glucose-enhanced (DGE) MRI has shown potential for imaging glucose delivery and blood brain barrier permeability. Previous reports focused on the technical development of DGE and only a few clinical brain tumor cases have been reported. Here we incorporated the current DGE protocol into our routine MRI examination at 3T and performed a small-scale clinical observational study on patients with different types of brain tumors. Despite the technical challenges of DGE at clinical scanners, we observed different (non)-enhancement patterns with various brain tumor types. |
| 3116 | Repeatability of Creatine Recovery Constants in Exercise Muscle Measured using 3D Creatine Chemical Exchange Saturation Transfer Imaging at 7T | |
| Dushyant Kumar1, Ravi Prakash Reddy Nanga1, Deepa Thakuri1, Abigail Cember1, Neil Wilson2, Hari Hariharan1, and Ravinder Reddy1 | ||
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Siemens Medical Solutions USA Inc, Malvern, PA, United States |
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Creatine CEST is a relatively new imaging technique, with the proven potential to assess the systemic energy deficiency in form of delayed creatine recovery in exercised skeletal muscles. However, this 2D method still suffers from limited volume coverage in slice encoding direction. Since the distribution of disease in many musculoskeletal disorders may vary across the muscle, there is a need to increase coverage in slice encoding direction. Towards this goal, we demonstrate the feasibility of 3D CrCEST, while still maintaining 30s time resolution necessary to capture underlying dynamics and also demonstrate its repeatability using data from five healthy volunteers. |
| 3117 | Accelerated 3D chemical exchange saturation transfer imaging using compressed SENSE for full Z-spectrum acquisition | |
| Tatsuhiro Wada1, Chiaki Tokunaga1, Osamu Togao2, Masami Yoneyama3, Yasuo Yamashita1, Kouji Kobayashi1, Toyoyuki Kato1, and Hidetake Yabuuchi4 | ||
1Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Japan, 2Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan, 3Philips Japan, Fukuoka, Japan, 4Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan |
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Multi-slice chemical exchange saturation transfer (CEST) imaging is difficult to use for clinical studies because data acquisition of the full z-spectrum is time-consuming. To accelerate the scan time for obtaining multi-slice CEST imaging, we applied the compressed sensing (CS) and sensitivity encoding (SENSE) technique (CS-SENSE) to 3D CEST imaging. The 3D CEST imaging combined with CS-SENSE was obtained without reducing the image contrast of the 2D CEST imaging. Moreover, 10 slice CEST images could be acquired in approximately 7 minutes including B0 map. 3D CEST imaging combined with CS-SENSE was shown to be useful for clinical study. |
| 3118 | A Steady State Approach to Positive Contrast Chemical Exchange Imaging using RACETE | |
| Fabian Tobias Gutjahr1,2, Simon Mayer2, and Peter M Jakob2 | ||
1Comprehensive Heart Failure Center, University Hospital Wuerzburg, Wuerzburg, Germany, 2Experimental Physics 5, University Wuerzburg, Wuerzburg, Germany |
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RACETE is a novel method for positive contrast imaging of chemical exchange. In this work the RACETE sequence is extended to allow steady state imaging by interleaving the preparation with small flip angle RACETE read-outs. It can be shown that the efficiency of the steady state RACETE is improved over the equilibrium RACETE. This is an important step towards speeding up the acquisition process to make RACETE a viable option for future in vivo experiments. |
| 3119 | Inulin as a biodegradable contrast agent for CEST MRI | |
| Anina Seidemo1, Malte Knutsson2, Patrick M. Lehmann1, Pia C. Sundgren3,4, Anthony Aletras5,6, Peter C.M. van Zijl7,8, and Linda Knutsson1,7 | ||
1Department of Medical Radiation Physics, Lund University, Lund, Sweden, 2Procivitas, Malmö, Sweden, 3Department of Diagnostic Radiology, Lund University, Lund, Sweden, 4Lund University Bioimaging Center, Lund University, Lund, Sweden, 5Department of Clinical Physiology, Clinical Sciences, Lund University and Lund University Hospital, Lund, Sweden, 6Laboratory of Computing and Medical Informatics, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece, 7Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 8F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States |
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GlucoCEST (chemical exchange saturation transfer imaging using glucose as a contrast agent) has shown potential in tumor imaging. However, glucose enters cells and is rapidly metabolized, leading to disappearance of the glucoCEST signal over time. Inulin, a polysaccharide, is non-toxic and acts like an intravascular tracer when injected intravenously. A phantom including both glucose and inulin at different pH and concentrations was scanned at 3T to investigate the potential of inulin as a CEST agent. This study indicates that inulin shows CEST contrast comparable to glucose on a per-OH-unit basis and has potential as a biodegradable CEST agent. |
| 3120 | Application of GluCEST in monitoring abnormal glutamate dehydrogenase activity in Hyperinsulinism/Hyperammonemia (HI/HA) syndrome at 7.0T | |
| Ravi Prakash Reddy Nanga1, Elizabeth A Rosenfeld2, Deepa Thakuri1, Mark Elliott1, Ravinder Reddy1, and Diva D De Leon2 | ||
1Radiology, Perelman School of Medicine at The University of Pennsylvania, Philadelphia, PA, United States, 2Division of Endocrinology and Diabetes, Children's Hospital of Philadelphia, Philadelphia, PA, United States |
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Hyperinsulinism/Hyperammonemia (HI/HA) syndrome is an orphan disease characterized by fasting and protein-induced hypoglycemia, hyperammonemia, and has high prevalence of epilepsy, developmental delays, and learning disabilities. Understanding the mechanism involved in brain phenotype remains limited. Glutamate weighted chemical exchange saturation transfer (GluCEST) imaging was used to spatially map the glutamate levels of hippocampus. We observed a higher GluCEST contrast in the hippocampus of some of these subjects following a unilateral pattern. This preliminary study demonstrates for the first time the application of GluCEST MRI for studying the abnormal function of glutamate dehydrogenase (GDH) enzyme activity in human subjects with HI/HA syndrome. |
| 3121 | Optimized CEST acquisition and analysis for treatment assessment of response to neoadjuvant chemotherapy in triple negative breast cancer | |
| Shu Zhang1, Abeer H. Abdelhafez2, Jong Bum Son3, Benjamin C. Musall3, Mitsuharu Miyoshi4, Xinzeng Wang5, Ken-Pin Hwang3, Gaiane M. Rauch2, Jingfei Ma3, and Mark D. Pagel1 | ||
1Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 2Abdominal Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 3Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 4Global MR Applications & Workflow, GE Healthcare Japan, Tokyo, Japan, 5Global MR Applications & Workflow, GE Healthcare, Houston, TX, United States |
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In our ongoing study of 13 completed patients, we compared two saturation power levels (2.0 μT vs. 0.9 μT) and two analysis methods (MTRasym vs. Lorentzian line fitting) of CEST for assessing treatment response to neoadjuvant chemotherapy of triple-negative breast cancer (TNBC). A consistently decreasing trend of the CEST signals was observed with the longitudinal treatment when a higher saturation power of 2.0 μT was used with the amide MTRasym analysis method. In contrast, the same trend was observed when a lower saturation power of 0.9 μT was used for the Lorentzian line fitting analysis method. |
| 3122 | Development of a standard phantom for Chemical Exchange Saturation Transfer MRI | |
| Shu Zhang1, F. William Schuler1, Tianzhe Li1, Ken-Pin Hwang2, Mitsuharu Miyoshi3, Xinzeng Wang4, and Mark D. Pagel1 | ||
1Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 2Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 3Global MR Applications & Workflow, GE Healthcare Japan, Tokyo, Japan, 4Global MR Applications & Workflow, GE Healthcare, Houston, TX, United States |
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Many clinical CEST MRI methods have been developed and disseminated during the last few years, and the expansion of clinical CEST MRI will likely continue. A common phantom is needed to standardize the development and implementation of CEST methods. In this study, we have developed a clinical CEST MRI phantom with high-quality gelatin to test a range of concentrations, pH values, and T1 relaxation times. The experimental conditions of the CEST saturation and various post-saturation acquisition methods can be tested. This standard phantom can be used to support many applications within the CEST MRI research community. |
| 3123 | Alzheimer’s Disease identification by an artificial neutral network based on chemical exchange saturation transfer (ANNCEST) MRI | |
| Joseph H. C. Lai1, Jianpan Huang1, Xiongqi Han1, Jiadi Xu2,3, and Kannie W. Y. Chan1,2 | ||
1Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, Hong Kong, 2Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 3F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, United States |
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There is an urgent need to develop an efficient and noninvasive methods to diagnose AD at an early stage. Artificial neural network (ANN) is a powerful model for prediction and classification of diseases, thus, it has been applied to facilitate prognosis and diagnosis. We propose to apply ANN based on chemical exchange saturation transfer (CEST) MRI at 3T to detect AD. Our phantom and AD mouse results showed that the trained ANN was able to identify AD from age-matched wild-type (WT) mice with high accuracy, which could provide valuable information for AD diagnosis. |
| 3124 | The perfusion contributing significantly to the CEST signal acquired by a UTE-CEST sequence | |
| Quan Tao1, Peiwei Yi1, Zimeng Cai1, Yingjie Mei2, Zhifeng Chen1, Ruiyuan Liu1, Wufan Chen1, and Yanqiu Feng1 | ||
1School of Biomedical Engineering, Southern Medical University, Guangzhou, China, 2Philips healthcare, Guangzhou, China |
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Chemical exchange saturation transfer (CEST) as a novel molecule MRI technique, was approved to detect some diseases, like tumor grading, kidney injure, osteoarthritis (OA) and etc. However, it is crucial to purify the CEST signal. In this study, we explored the perfusion contribution to the CEST signal acquired by a UTE-CEST sequence. |
| 3125 | In Vitro Characterization of Serotonin Biosynthesis Pathway by CEST MRI | |
| Ryan T Oglesby1,2, Wilfred W Lam2, and Greg J Stanisz1,2 | ||
1Medical Biophysics, University of Toronto, Toronto, ON, Canada, 2Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada |
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This study demonstrates the in vitro characterization of tryptophan, 5-HTP, serotonin (5-HT), 5-HIAA (all members of the serotonin biosynthesis pathway), and melatonin at precise pH, temperature, and concentration. At pH 5.5, CEST contrast between 0.6 and 1.9 ppm, originating from the NH3+ side chain, is exhibited by tryptophan, 5-HTP, and 5-HT. All five molecules at pH 7.4 exhibit CEST contrast between 5.11 and 5.47 ppm, originating from the NH proton on the indole ring. If sensitive enough in vivo, these measurements could improve the objectivity of clinically diagnosed psychiatric disorders and could provide a new biological understanding of serotonergic dysfunction. |
| 3126 | Fast 2D EPI multislice imaging for full APT-CEST brain coverage | |
| Jan-Rüdiger Schüre1, Manoj Shrestha2, Eike Steidl3, Ralf Deichmann2, Elke Hattingen3, Marlies Wagner3, and Ulrich Pilatus3 | ||
1Neuroradiology, Goethe University Hospital, Frankfurt am Main, Germany, 2Brain Imaging Center (BIC), Frankfurt am Main, Germany, 3Goethe University Hospital, Frankfurt am Main, Germany |
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We present a fast 2D EPI multislice sequence that allows to acquire the APT-CEST contrast in 16 slices within 8 seconds. The fast CEST-EPI sequence was compared in vitro and in vivo with a steady-state CEST sequence, where the saturation is applied for 4 s for each frequency offset. The reduced acquisition time in the fast sequence can be used for measurement repetitions or additional MR examinations (e.g. MR spectroscopic imaging). |
| 3127 | Investigation of the reliability in pH quantification with MR chemical exchange saturation transfer (CEST) power ratiometric imaging at 3 Tesla | |
| Jie Liu1, Zongwei Xu1, Qi Liu2, Hui Liu2, Jian Xu2, Xin Liu1, Hairong Zheng1, and Yin Wu1 | ||
1Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, 2United Imaging Healthcare America, Houston, TX, United States |
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Chemical exchange saturation transfer (CEST) using iodinated agents has been tested for extracellular pH imaging on high-field animal scanners. However, the reliability in the pH quantification on low magnetic strengths remains elucidated. In this study, CEST imaging was performed on iobitridol phantom twice with a three-day interval at 3T. pH was quantified by ratioing iobitridol CEST effects at 5.6 ppm under B1 of 1.0 and 2.0 μT. Results show accurate pH quantification in both scans. Good consistency of paired measures was observed between the two scans, suggesting the reliability of the method and its potential clinical applicability at 3T. |
| 3128 | Concentration-independent absolute pH mapping using amide CEST-MRI at 9.4 T | |
| Philip S. Boyd1, Johannes Breitling1, Mark E. Ladd1, Peter Bachert1, and Steffen Goerke1 | ||
1Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany |
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In this study, we developed an absolute pH mapping method based on endogenous amide CEST-MRI which simultaneously compensates for concentration changes, the semi-solid magnetization transfer, and spillover dilution. This was realized by a ratiometric approach of two different B1 in combination with the inverse metric and polynomial Lorentzian-fitting of the amide signal. Compensation for concomitant effects was theoretically demonstrated in simulations and verified experimentally in protein model solutions and porcine brain lysates. Consequently, amide signal-based absolute pH mapping is now in principle also reliably applicable for tumor imaging which was previously prevented by the concomitant effects. |
| 3129 | Turnkey qMT via Selective Inversion Recovery | |
| Richard Dortch1 | ||
1Division of Neuroimaging Research, Barrow Neurological Institute, Phoenix, AZ, United States |
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MTR offers a measure of myelin content, but is also sensitive to non-physiological parameters. Quantitative MT methods remove these confounding effects; however, they require long scan times and complicated acquisition/analysis strategies. Selective inversion recovery is a simple method that may address many of these limitations, but requires long scan times and specialized inversion recovery sequences. The issue of long scan times was previously addressed through optimized sampling schemes. The need for specialized sequences is addressed herein by using a standard MP-RAGE sequence and modifying the SIR signal model. The resulting “turnkey” approach was tested numerically and applied in the brain. |
| 3130 | pH mapping of brain tissue by a deep neural network trained on 9.4T CEST MRI data – pH-deepCEST | |
| Sebastian Mueller1, Felix Glang1, Klaus Scheffler1,2, and Moritz Zaiss1,3 | ||
1High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, 2Department of Biomedical Magnetic Resonance, Eberhard Karls University Tuebingen, Tuebingen, Germany, 3Department of Neuroradiology, University Hospital Erlangen, Erlangen, Germany |
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The pH value is of major importance for most physiological processes and may change due to altered metabolism in pathologies. In the present work, we exploit the inherent dependency of CEST MR data on pH with a new approach: train neural networks to map voxel-by-voxel from multi-B1+ CEST spectra to pH value. Measurements were performed in homogenate of pig brain tissue at 9.4T ultra high field. Prediction of absolute pH values was possible and predictions were stable against inhomogeneity in B1+. We hope this proof of concept might be a first small step towards high-resolution 3D pH maps in vivo. |
| 3131 | The cellular heat shock response monitored by chemical exchange saturation transfer MRI | |
| Dennis Kleimaier1, Steffen Goerke2, Cordula Nies3, Moritz Zaiss4, Patrick Kunz5, Eric Gottwald3, and Lothar R. Schad1 | ||
1Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany, 2Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 3Institute of Functional Interfaces, Karlsruhe Institut of Technology, Karlsruhe, Germany, 4Neuroradiology, University of Erlangen-Nürnberg, Erlangen, Germany, 5Division of Functional Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany |
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Chemical exchange saturation transfer of the relayed nuclear Overhauser effect(rNOE) enables detection of mobile protein protons via their exchange with the water signal. Recent studies have shown a close relationship between the rNOE-signal and the protein conformation. This study used the -3.5ppm rNOE-signal to monitor the heat shock response of HepG2 cells in a microcavity array-based bioreactor system. A significant drop of the rNOE-signal to 92.4±1.3% and a slow, steady increase of the rNOE-signal for 136.1±13.6min after heat shock were observed. Therefore, the rNOE-signal in CEST spectroscopic imaging is a sensitive readout for the cellular heat shock response. |
| 3132 | qMTNet: Accelerated Quantitative Magnetization Transfer Imaging with Neural Networks | |
| Huan Minh Luu1, Dong-Hyun Kim1, Jae-Woong Kim1, Seung-Hong Choi2, and Sung-Hong Park1 | ||
1Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea, 2Department of Radiology, Seoul National University Hospital, Seoul, Republic of Korea |
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Quantitative magnetization transfer (qMT) imaging overcomes the drawbacks of traditional MT imaging by producing more quantitative parameters. However, data acquisition and processing can be time-consuming, which limits its usage. In this study, an artificial neural network, qMTNet, is proposed to accelerate both the acquisition and fitting of qMT data. For data acquired from both conventional and inter-slice acquisition strategies, our approach demonstrated consistent fitting results with those from a previous dictionary-driven fitting method. The network reduces the time for both data acquisition and qMT fitting by a factor of 3 and 5000 times, respectively, compared to the conventional methods. |
| 3133 | One Minute Whole-Brain Magnetization Transfer Ratio Imaging with Intrinsic B1-Correction | |
| Roya Afshari1,2, Francesco Santini1,2, Rahel Heule3, Craig H. Meyer4, Josef Pfeuffer5, and Oliver Bieri1,2 | ||
1Division of Radiological Physics,Department of Radiology, University Hospital Basel, University of Basel, Basel, Switzerland, 2Department of Biomedical Engineering, University of Basel, Basel, Switzerland, 3High Field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 4Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, 5Siemens Healthcare, Application Development, Erlangen, Germany |
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Magnetization transfer (MT), reflecting the exchange of magnetization between mobile and bound protons, has shown good potential for the diagnosis and prognosis of various neurological disorders, such as multiple sclerosis. Frequently, MT effects are assessed by measuring the contrast between two scans performed with and without saturation of the bound pool protons. Evidently, saturation is affected by B1 inhomogeneity and should be accounted for. In this work, we report on a very rapid one-minute whole-brain magnetization transfer ratio (MTR) imaging method offering intrinsic B1-correction. |
| 3134 | Enhancing Magnetization Transfer Contrast (MTC): A proof-of-concept study of MTC-STAGE Imaging | |
| Jun Chen Li1,2, Yu Liu1, Yongsheng Chen3, Zhijia Jin1, Naying He1, Weibo Chen4, Fuhua Yan1, and Ewart Mark Haacke1,5,6 | ||
1Radiology, Ruijin Hospital, Shanghai, China, 2Radiology, Changshu Hospital Affiliated to Nanjing University of Chinese Medicine, Changshu, China, 3Neurology, Wayne State University, Detroit, MI, United States, 4Philips Healthcare, Shanghai, China, 5Radiology, Wayne State University, Detroit, MI, United States, 6Biomedical Engineering, Wayne State University, Detroit, MI, United States |
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Magnetization transfer contrast (MTC) imaging has been used to study neuromelanin (NM) in Parkinson’s disease. By suppressing the background tissue using an MTC pulse in a T1W sequence, the NM becomes visible, supposedly because of its reduced T1. However, we show using STAGE (strategically acquired gradient echo) imaging with/without an MTC pulse that this is not the reason for its visibility. Rather, it is the increased water content relative to surrounding tissue that keeps the signal high. Using the appropriate choice of flip angles and resolution, the NM contrast on MTC images can be significantly increased. |
| 3135 | Quantitative magnetization transfer (MT) of tissue from subjects with multiple sclerosis using inhomogeneous MT (ihMT) data | |
| Gopal Varma1, Hemant Varma2, Cody Callahan1, Olivier M Girard3, Guillaume Duhamel3, Aaron K Grant1, and David C Alsop1 | ||
1Division of MR Research, Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, 2Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, 3CNRS, CRMBM, Aix-Marseille Univ, Marseille, France |
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Quantitative magnetization transfer (MT) was carried out using inhomogeneous MT (ihMT) data, following optimization of an acquisition protocol. The optimized protocol was applied in ex-vivo brain tissue from a donor with multiple sclerosis (MS), as well as tissue containing an MS plaque. Parameter maps output from quantitative MT showed white and grey matter contrast, as well as a lower restricted or bound pool fraction in the area of the MS plaque from histology. Results from quantitative MT using ihMT were compared with those using selective inversion recovery, as well as quantitative outputs from diffusion tensor MRI. |
| 3136 | Inhomogeneous magnetization transfer saturation (ihMTsat): efficient centric-encoded GRE implementation with B1 inhomogeneity correction | |
| Christopher D Rowley1,2, Zhe Wu2,3, Ilana R. Leppert2, Jennifer S.W. Campbell 2, David A. Rudko2,4,5, G. Bruce Pike6, and Christine L. Tardif1,2,4 | ||
1Neurology and Neurosurgery, McGill University, Montreal, QC, Canada, 2McConnell Brain Imaging Center, McGill Unversity, Montreal, QC, Canada, 3Techna Institute, University Health Network, Toronto, ON, Canada, 4Department of Biomedical Engineering, McGill Unversity, Montreal, QC, Canada, 5Department of Neurology and Neurosurgery, McGill Unversity, Montreal, QC, Canada, 6Hotchkiss Brain Institute and Departments of Radiology and Clinical Neuroscience, University of Calgary, Calgary, AB, Canada |
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Inhomogeneous magnetization transfer (ihMT) contrast in the brain has been reported to be a myelin-specific biomarker, but can be impacted by B1 inhomogeneities, reducing its accuracy. ihMT equations incorporating B1 correction assume a single excitation and readout, either a k-space line or plane, per saturation module. Here we use an arbitrary number of readout segments collected after an MT saturation preparation module. T1 and B1 variations are included in the signal equations to increase specificity of the contrast to the microstructure. The resulting implementation yields a balance between acquisition efficiency and contrast resolution for different brain imaging applications. |
| 3137 | Accelerated quantitative magnetization transfer (qMT) imaging using compressed sensing and parallel imaging | |
| Melany McLean1, R. Marc Lebel1,2, M. Ethan MacDonald1, Mathieu Boudreau3,4, and G. Bruce Pike1 | ||
1Departments of Radiology and Clinical Neuroscience, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada, 2GE Healthcare, Calgary, AB, Canada, 3Montreal Heart Institute, Université de Montreal, Montreal, QC, Canada, 4NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada |
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Quantitative magnetization transfer (qMT) is a Z-spectrum based imaging technique used to study white matter. The need to acquire many images with unique RF saturation pulses leads to long acquisition times. We aim to shorten qMT imaging times using a sparseSENSE technique that combines parallel imaging and compressed sensing to reduce the amount of acquired data. Retrospectively undersampled data was reconstructed for a range of acceleration factors using wavelet and total variation sparsifying domains. Pool size ratio (F) maps were accelerated by a factor of 4×, and acceleration factors of 8-12× may be possible in future work. |
| 3138 | High-resolution magnetization transfer ratio maps using spiral-phyllotaxis Cartesian FLASH and compressed sensing in under five minutes | |
| Gabriele Bonanno1,2,3, Tom Hilbert4,5,6, Arun Joseph1,2,3, Emilie Mussard4,5,6, Christoph Forman7, Gian Franco Piredda4,5,6, and Tobias Kober4,5,6 | ||
1Advanced Clinical Imaging Technology, Siemens Healthcare AG, Bern, Switzerland, 2Translational Imaging Center, sitem-insel AG, Bern, Switzerland, 3Departments of Radiology and Biomedical Research, University of Berne, Bern, Switzerland, 4Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland, 5Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, 6LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 7Magnetic Resonance, Siemens Healthcare GmbH, Erlangen, Germany |
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Magnetization Transfer Ratio (MTR) imaging may be a valuable tool for the diagnosis and follow-up of demyelinating diseases. However, MTR maps require long scan times for whole-brain coverage and high isotropic resolution. We present a novel MTR imaging method based on a spiral-phyllotaxis Cartesian FLASH sequence and compressed sensing, called MTRSparse, and compare it to fully sampled and parallel-imaging-accelerated acquisitions in healthy volunteers. MTRSparse showed good contrast and similar MTR values in comparison to the reference method with up to 87% reduction in acquisition time. This can help facilitate implementation of MTR imaging in the clinical practice. |
| 3139 | Estimation of Glutamate-weighted CEST Contrast after Removal of Magnetization Transfer Effect in Human Brain and Rat Brain with Tumor | |
| Ayan Debnath1,2, Hari Hariharan2, Ravi Prakash Reddy Nanga2, Ravinder Reddy2, and Anup Singh1,3 | ||
1Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India, 2Center for Magnetic Resonance & Optical Imaging, University of Pennsylvania, Philadelphia, PA, United States, 3Department of Biomedical Engineering, All India Institute of Medical Science, New Delhi, India |
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Asymmetry in MT causes erroneous GluCEST computation. The study focuses on removal of MT effects from Z-spectra for better quantification of GluCEST contrast using in-vivo human volunteer at 7T and rat brain with tumor at 9.4T. Different lineshapes for modelling and fitting broad MT spectrum has been compared. Lorentzian lineshape provided significant difference between GluCEST contrast before and after MT removal and also preserves the gray-matter to white-matter glutamate concentration ratio validated with MR spectroscopic based estimation. After removal of MT effect using Lorentzian lineshape, the specificity of GluCEST to glutamate concentration increases which can helps better diagnosis of diseases. |
| 3140 | Variable-density Fast-Spin-Echo (FSE) for volumetric inhomogeneous Magnetization Transfer (ihMT) imaging | |
| Manuel Taso1, Fanny Munsch1, Arnaud Guidon2, Olivier M. Girard3, Guillaume Duhamel3, David C. Alsop1, and Gopal Varma1 | ||
1Division of MRI research, Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, 2Global MR Applications and Workflow, GE Healthcare, Boston, MA, United States, 3CRMBM, Aix-Marseille Univ, CNRS, Marseille, France |
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While the original inhomogeneous magnetization transfer (ihMT) implementations for myelin imaging relied heavily on single-slice imaging, recent developments have enabled volumetric acquisitions using rapid gradient-echo sequences. But in vivo volumetric spin-echo acquisitions have been unexplored so far although they provide a theoretical advantage over GRE. We report here the implementation of a variable-density FSE with Compressed-Sensing for time-efficient volumetric ihMT imaging with high SNR. Provisional experiments show promising results even at high acceleration rates while also identifying areas for potential improvement, paving the way for future use of ihMT FSE for whole brain and potentially spinal cord imaging. |
| 3141 | Magnetization transfer contrast (MTC) suppressed relayed nuclear Overhauser enhancement (rNOE) imaging at 3 T | |
| Jianpan Huang1, Xiongqi Han1, Lin Chen2,3, Xiang Xu2,3, Peter C. M. van Zijl2,3, Jiadi Xu2,3, and Kannie W. Y. Chan1,2 | ||
1Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China, 2Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States, 3F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, United States |
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Relayed nuclear Overhauser enhancement (rNOE) imaging indirectly detects the aliphatic groups of biomolecules and can be used to diagnose protein or lipid signals and related pathology involving such signals. Current rNOE imaging has been studied mainly on high-field MRI scanners (≥7T). When implementing the technique on low clinical MRI fields (≤3T), rNOE contrast is more obscured by semisolid magnetization transfer contrast (MTC) and water direct saturation (DS). We developed a pulsed-CEST/MT method at 3T MRI that can suppress MTC and DS efficiently, not compromising rNOE contrast. |
| 3142 | Quantification of Magnetization Transfer and Inhomogeneous Magnetization Transfer with an MPRAGE sequence and an MTsat Approach | |
| David C Alsop1, Fanny Munsch1, Gopal Varma1, Olivier Girard2, and Guillaume Duhamel2 | ||
1Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States, 2CRMBM, Aix Marseille Univ, CNRS, Marseille, France |
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Methods for quantification of Inhomogeneous Magnetization Transfer (ihMT), are not yet well established. This is especially true for ihMT prepared sequences such as ihMT MPRAGE, where no steady state solution is available. Here we adapt the MTsat approach to quantification of MT and ihMT in an MPRAGE sequence. |
| 3143 | Analytic solution for macromolecular proton fraction (MPF) determined from single point magnetization transfer experiment | |
| Kimberly L. Desmond1 | ||
1Research Imaging Centre, CAMH, Toronto, ON, Canada |
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Single point magnetization transfer (MT) is a quantitative method which reduces the number of unknowns in the MT signal equation by fixing tissue parameters which are effectively constant such that the macromolecular proton fraction (MPF) is the only remaining variable. In this work, the nonlinear signal equation describing single point MT was inverted to obtain an analytic expression for MPF as a function of observed normalized signal (MT∆/MT0). This enables rapid computation of MPF maps from matrix operations performed on the 3D images of the MT-weighted image (MT∆), the MT reference image, (MT0), and separately acquired T1 and B1 maps. |
| 3144 | Distinguishing between macromolecular-driven magnetization transfer (MTSAT) and direct water saturation (MTDIR) | |
| Dvir Radunsky1, Tamar Blumenfeld-Katzir1, and Noam Ben-Eliezer1,2,3 | ||
1Bio-medical Engineering, Tel Aviv University, Tel Aviv, Israel, 2Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel, 3Center for Advanced Imaging Innovation and Research (CAI2R), New-York University Langone Medical Center, New York, NY, United States |
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Mapping of T2 values is highly valuable for a wide range of applications. Still, accurate mapping is challenging due to the inherent bias of rapid Multi-Echo Spin-Echo (MESE) protocols by stimulated echoes, and also by magnetization transfer (MT). In this work, we investigate the different effects of macromolecular-driven MT (MTSAT) and direct water saturation (MTDIR) mechanisms on MESE signals, and their respective influence on T2 values. The investigation includes quantitative MT measurements between protocols with different scan settings and protocol schemes, aiming to isolate the individual roles of MTSAT and MTDIR. |
| 3145 | An Analysis of Post-Radiation Response in DU145 Prostate Tumour Xenografts Using Magnetization Transfer MRI | |
| Leedan Murray1, Wendy Oakden1, Wilfred W. Lam1, and Greg J. Stanisz1 | ||
1Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada |
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The response to radiation treatment of DU145 prostate tumour xenografts was studied by comparing magnetization transfer-weighted Z-spectra before and after treatment. ROIs were drawn in homogenous sections of the tumour and analyzed based on corresponding TUNEL histology images. MTR decreased more than 1 week post-treatment in tumours that responded to treatment but was unchanged for non-responding tumours. The technique introduced in this study could potentially introduce a non-invasive way of determining treatment efficacy based on tumour necrosis/apoptosis. |
| 3146 | Towards understanding of CEST signal in breast cancer; relation between APT- MT- and B1 effects. | |
| Elles Elschot1, Lieke van den Wildenberg1, Vitaly Khlebnikov1, Dennis Klomp1, and Jannie Wijnen1 | ||
1Radiology Department, UMC Utrecht, Utrecht, Netherlands |
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This study investigates the relation between B1+ and signal amplitude of the APT and MT exchange pools in CEST MRI. We examined 19 breast cancer patients that underwent NAC treatment with CEST MRI at 7T. The data indicates evidence for an extra exchanging pool with strong B1 dependence, that is more abundant in tumor tissue compared to healthy tissue. By identifying the exchanging components in this pool, a new biomarker for tumor tissue could be found and used to understand changes in response to NAC early during treatment. |
| 3147 | Alternating 3D Unbalanced SSFP With Z-shimming for Background Field Corrected R2’ Measurement in the Human Brain | |
| Hyunyeol Lee1, Dongyeop Han2, Cheng-Chieh Cheng1, and Felix W Wehrli1 | ||
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Electrical and Electronic Engineering, Yonsei University, Seoul, Korea, Republic of |
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The relaxation parameter R2’ characterizes susceptibility-induced voxel signal modulations, for example, in the presence of deoxygenated hemoglobin in brain microvasculature or iron deposits in deep gray matter structures. Current R2’ measurement methods build on a spin-echo sequence configuration, and hence require impractically long scan time for volumetric 3D R2’ mapping. Furthermore, large susceptibility gradients around air/tissue interfaces result in signal distortions with increasing echo times, thus making it challenging to achieve accurate R2’ estimation in deep GM regions. Here, we propose an alternating, 3D z-shimmed, unbalanced steady-state-free-precession (SSFP) technique for rapid and B0-corrected R2’ mapping in the human brain. |
| 3148 | Assessment of R2* dependency on fiber orientation and myelin concentration in normal-appearing white matter in multiple sclerosis | |
| Renat Sibgatulin1, Daniel Güllmar1, Andreas Deistung2, Stefan Ropele3, and Jürgen Rainer Reichenbach1,4,5,6 | ||
1Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany, 2Department of Radiology, University Hospital Halle (Saale), Halle, Germany, 3Department of Neurology, Medical University of Graz, Graz, Austria, 4Michael Stifel Center Jena for Data-Driven and Simulation Science, Friedrich Schiller University Jena, Jena, Germany, 5Abbe School of Photonics, Friedrich Schiller University Jena, Jena, Germany, 6Center of Medical Optics and Photonics, Friedrich Schiller University Jena, Jena, Germany |
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The effective transverse relaxation rate (R2*) is increasingly used in quantitative MRI, due to its sensitivity to iron and myelin content of the tissue. Separating the contributions from both sources is of particular interest in relation to multiple sclerosis. This work attempts to factor out contribution from myelin using orientation information derived from dMRI, and magnetization transfer saturation (MTS). Application of such correction to a group of multiple sclerosis patients and a control group, suggests that sensitivity of R2* to iron might be improved by accounting for fiber orientation in WM, while incorporation of MTS might not show clear benefit. |
| 3149 | Fat DESPOT for MR-oximetry validated by STEAM MRS | |
| Véronique Fortier1,2 and Ives R. Levesque1,2,3 | ||
1Medical Physics Unit, McGill University, Montreal, QC, Canada, 2Biomedical Engineering, McGill University, Montreal, QC, Canada, 3Research Institute of the McGill University Health Centre, Montreal, QC, Canada |
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The R1 relaxation rate of fat is a promising biomarker for mapping tissue oxygenation. Existing techniques to map fat R1 are limited to single-voxel or 2D imaging with long scan times. To address these limitations, this work presents a 3D technique to map fat R1 using a fat-water-separated variable flip angle (VFA) approach. The sensitivity of this technique to oxygenation variations was evaluated in a phantom. The results showed that fat R1 can be measured using a technique based on 3D VFA at 3 T and is feasible for MR-oximetry. |
| 3150 | T1 relaxation in fat and its dependence on fat content | |
| Véronique Fortier1,2 and Ives R. Levesque1,2,3 | ||
1Medical Physics Unit, McGill University, Montreal, QC, Canada, 2Biomedical Engineering, McGill University, Montreal, QC, Canada, 3Research Institute of the McGill University Health Centre, Montreal, QC, Canada |
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The T1 relaxation of triglyceride molecules is of interest for fat-water separation and fat quantification. A better understanding of the T1 of fat could benefit modeling techniques for applications in MR-oximetry and fatty liver disease. In this work, the T1 relaxation and its dependence on fat content was evaluated for five spectral peaks present in triglyceride molecules, over a range of fat fractions in a homogeneous fat-water mixture. The T1 of water in mixture was also studied. A model is proposed to describe the two-pool relaxation in a fat-water mixture as a function of the fraction of each pool. |
| 3151 | Multi-seed myelin water imaging using gradient echo: beyond the initial guess in exponential-sum fit | |
| Hyeong-Geol Shin1, Se-Hong Oh2, Sooyeon Ji1, Jieun Lee1, Woojin Jung1, Eun-Jung Choi1, and Jongho Lee1 | ||
1Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of, 2Biomedical Engineering, Hankuk University of Foreign Studies, Yongin, Korea, Republic of |
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In this work, we investigated the effects of initial parameter guess on non-linear least square (NLLS) method for myelin water imaging (MWI). We demonstrated that an inappropriate initial guess induces error in MWI and proposed a multi-seed algorithm to reduce the initial guess-dependent error. To do so, we applied the multi-seed MWI to synthetic and in-vivo data and compared the outcomes with the conventional algorithm (i.e., single-seed MWI). MWI results estimated by the multi-seed algorithm showed better agreement with the model than the single-seed algorithm, suggesting a potential solution to mitigate the ill-posed condition of MWI. |
| 3152 | Adaptive and slice-specific z-shimming approach for signal rephasing in 2D multi gradient echo imaging | |
| Martin Soellradl1, Johannes Strasser1, Stefan Ropele1, and Christian Langkammer1 | ||
1Department of Neurology, Medical University of Graz, Graz, Austria |
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Intravoxel dephasing due to macroscopic field variations along the slice-selective direction z can be compensated by application of compensation gradients in z-direction (“z-shimming”). Compensation gradients applied between echo acquisition allow to estimate R2* also in areas with strong field gradients. However, if equally strong compensation gradients are applied in each slice the signal dephases in homogenous areas. We therefore propose an adaptive method where slice-specific compensation gradients are estimated for each slice from a fast pre-scan. With the proposed approach improved R2*-maps, compared to constant compensation gradient strategies, with higher SNR and accuracy can be achieved. |
| 3153 | Relaxometry Differences Between Magno- and Parvocellular Human LGN Subdivisions Revealed by In- and Ex-vivo Quantitative MRI | |
| Christa Müller-Axt1,2, Cornelius Eichner1, Louise Kauffmann1,3, Pierre-Louis Bazin1,4, Henriette Rusch5, Markus Morawski5, Alfred Anwander1, and Katharina von Kriegstein2 | ||
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 2Faculty of Psychology, Technical University of Dresden, Dresden, Germany, 3LPNC, Grenoble Alpes University, Grenoble, France, 4Integrative Model-based Cognitive Neuroscience Research Unit, Department of Psychology, University of Amsterdam, Amsterdam, Netherlands, 5Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany |
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The human lateral geniculate nucleus (LGN) is the central station for visual processing before information reaches the cerebral cortex. It is characterized by subdivisions with distinct cyto- and myeloarchitecture. Due to its small size, imaging of the LGN and especially its subdivisions is challenging. Here, we show that the LGN and its subdivisions can be identified using in-vivo and ex-vivo high-field quantitative MRI with ultra-high resolution. We present the to-date first atlas of the LGN and its estimated subdivisions. This work will serve as a highly valuable tool both for neuroscientists and clinicians investigating the visual system and its disorders. |
| 3154 | Quantitative Imaging Metrics Derived from MR Fingerprinting using ISMRM/NIST System Phantom: An International Multi-Center Test-Retest Study | |
| Amaresha Konar Shridhar1, Enlin Qian2, Sairam Geethanath2, Guido Buonincontri3, Maggie M Fung4, Nancy A Obuchowski5, Pedro Gomez6, Rolf Schulte7, Lawrence H Schwartz8, and Amita Shukla-Dave1,9 | ||
1Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, United States, 2Columbia Magnetic Resonance Research Center, Columbia University, New York, NY, United States, 3Imago7 Foundation, Pisa, Italy, 4MR Apps & Workflow, GE Healthcare, New York, NY, United States, 5Department of Quantitative Health Sciences, Cleveland Clinic Foundation, Cleveland, OH, United States, 6Global Research, GE Healthcare, Munich, Germany, 7MR Workflow & Application Team, GE Healthcare, New York, NY, United States, 8Department of Radiology, Columbia University Medical Center, New York, NY, United States, 9Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, United States |
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The present study performed the repeatability and reproducibility test for T1, and T2 values estimated using MR fingerprinting (MRF) method. MRF data have been acquired over 30 days at three different centers (center-1 (USA): 1.5T and 3T, center-2 (USA): 3T and center-3 (Italy): 1.5T) using ISMRM/NIST MRI system phantom. MRF based estimated T1 and T2 values are compared with the vendor provided values and standard inversion recovery spin echo and a multiple single-echo spin-echo method as scanner Ground Truth (GT) values. The results show that the T1 and T2 values estimated using the MRF method are highly repeatable and reproducible. |
| 3155 | An Efficient, Robust, and Reproducible Quantitative Radial T1 Mapping Technique | |
| Mahesh Bharath Keerthivasan1, Marcel Dominik Nickel2, Fei Han3, Xiaodong Zhong3, Maria Altbach4, Berthold Kiefer2, and Vibhas Deshpande5 | ||
1Siemens Healthcare USA, Tucson, AZ, United States, 2Siemens Healthcare Gmbh, Erlangen, Germany, 3Siemens Healthcare USA, Los Angeles, CA, United States, 4University of Arizona, Tucson, AZ, United States, 5Siemens Healthcare USA, Austin, TX, United States |
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There has been renewed interest in the estimation of T1 relaxation times as a quantitative method for characterization of pathologies in the abdomen. While various techniques have been presented for T1 mapping they have not been systematically evaluated. In this work, we present a multi-slice radial Look-Locker FLASH technique for robust and reproducible abdominal T1 mapping. We investigate the effect of various pulse sequence and reconstruction parameters on the T1 estimation performance. |
| 3156 | Low Field MR Thermometry with a Fast, Interleaved Look-Locker based T1 Mapping Approach. | |
| Marco Fiorito1, Maksym Yushchenko1, Mathieu Sarracanie1,2, and Najat Salameh1 | ||
1Laboratory for Adapatable MRI Technology (AMT lab), Dpt of Biomedical Engineering, University of Basel, Basel, Switzerland, 2Medical Image Analysis Centre (Miac AG), Basel, Switzerland |
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Low field scanners present several advantages for interventional applications, however no standard method has yet arisen from temperature mapping. In this study we investigated the relationship between T1 and temperature at 0.1 T. MR images of four water phantoms, characterised by different T1, were acquired at different temperatures using a multi-slice FLASH sequence based on Look-Locker. Pixel-wise estimation of T1 relaxation through data fitting showed a growing trend with temperature. In light of the large number of time points, compromising SNR by a factor of 2 produced similar results for an almost 4 times faster acquisition. |
| 3157 | A novel T2 relaxation analysis method SAME-ECOS: Spectrum Analysis for Multiple Exponentials via Experimental Condition Oriented Simulation | |
| Hanwen Liu1,2, Qing-San Xiang1,3, Roger Tam3,4, Piotr Kozlowski3, David K.B. Li3, Alex L. MacKay1,3, John K. Kramer2,5, and Cornelia Laule1,2,3,6 | ||
1Physics & Astronomy, University of British Columbia, Vancouver, BC, Canada, 2International Collaboration on Repair Discoveries, Vancouver, BC, Canada, 3Radiology, University of British Columbia, Vancouver, BC, Canada, 4Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada, 5Kinesiology, University of British Columbia, Vancouver, BC, Canada, 6Pathology & Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada |
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We propose a novel T2 relaxation data analysis method called spectrum analysis for multiple exponentials via experimental condition oriented simulation (SAME-ECOS), which was developed based on a combination of information theory and deep learning neural network algorithms. SAME-ECOS is tailored for different MR experimental conditions to decompose the multi-exponential decay data into a T2 spectrum, which has been considered an ill-posed problem using conventional fitting algorithms including the commonly used non-negative least squares (NNLS). Our results demonstrated that, compared with NNLS, SAME-ECOS can yield much more reliable T2 spectra in a dramatically shorter time. |
| 3158 | A Novel 10-echo GESE multi-parametric sequence based on the EPIK readout for simultaneous quantification of T2 and T2* | |
| Fabian Küppers1, Seong Dae Yun1, and Nadim Jon Shah1,2,3,4 | ||
1Institute of Neuroscience and Medicine 4, Forschungszentrum Jülich, Jülich, Germany, 2Department of Neurology, RWTH Aachen, Aachen, Germany, 3Institute of Neuroscience and Medicine 11, Forschungszentrum Jülich, Jülich, Germany, 4JARA - BRAIN - Translational Medicine, Aachen, Germany |
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MRI sequences with a mixed GE/SE signal have been shown to be suitable for a wide range of applications due to the wide variety of accessible parameters. This work presents in vivo results of a 10-echo GESE sequence based on an EPIK readout to demonstrate the feasibility of whole-brain acquisitions below 5min, including T2 and T2* maps; comparison is made to reference methods. The generated images are artefact free and the T2*-maps correspond with conventional multi-echo GE results. The T2 values are higher than those from conventional SE, but are correctable using a reduced TE and improved fitting. |
| 3159 | Accelerated reconstruction of T2 maps based on the echo modulation curve signal model, and using PCA and gradient-descent search algorithms | |
| Guy Shpringer1 and Noam Ben-Eliezer1,2,3 | ||
1Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel, 2Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel, 3Center for Advanced Imaging Innovation and Research (CAI2R), New-York University Langone Medical Center, New York, NY, United States |
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Quantification of T2 values is important for a wide range of research and clinical applications. The Echo modulation Curve Algorithm allows accurate mapping of T2 values at clinical scan-times based on multi-echo spin echo data. Reconstruction, however, is still done offline and requires 10’s of minutes of processing times, thereby hampering the integration of this technique into real-time applications. We present in this work two approaches for accelerating maps reconstruction, based on PCA and gradient descent search algorithm. These offer up to x20 acceleration in reconstruction time, and can be potentially generalized to other reconstruction procedures involving dictionary search. |
| 3160 | Joint estimation of PDFF and T1 in abdomen with simultaneous B1+ correction at 3T | |
| Hao Peng1,2, Liwen Wan1, Qian Wan1, Jianxun Lv1, Chuanli Cheng1, Xin Liu1, Hairong Zheng1, and Chao Zou1 | ||
1Shenzhen Institutes of Advanced Technology,Chinese Academy of Sciences, Shenzhen, China, 2Huazhong University of Science & Technology, Wuhan, China |
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T1 quantification is a valuable biomarker for liver function estimation and fibrosis staging. The presence of fat would confound the measurement of tissue T1. Chemical shift encoded fat-water separation combined variable flip angle (CSE-VFA) T1 mapping could remove the bias from fat signals, but B1 inhomogeneity would be a serious problem in abdominal applications. In this work, we proposed to combine the DREAM sequence with CSE-VFA, so that PDFF/T1/B1/R*2 could be simultaneously estimated. The deviation of the T1 values between the results with and without B1 correction verified the necessity of B1 measurements in the abdominal application. |
| 3161 | Multi-compartment T1 relaxometry with inversion recovery sequence: a fat-water phantom study | |
| Hao Peng1, Liwen Wan1, Qian Wan1, Chuanli Cheng1, Xin Liu1, Hairong Zheng1, and Chao Zou1 | ||
1Shenzhen Institutes of Advanced Technology,Chinese Academy of Sciences, Shenzhen, China |
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T1 relaxation time has been a valuable biomarker with emerging applications in cardiac diseases and liver function. Traditional inversion-recovery T1 quantification method is frequently applied as the reference for various T1 quantification methods. When applied in targets where fat and water signals co-exists, the single component fitting model would be in a dilemma. Combining the inversion-recovery T1 quantification with existing fat-water quantification methods, this work presented a solution for multi-component T1 quantification. Proposed method has been tested on fat-water phantoms and showed good consistency over a wide range of fat fractions. |
| 3162 | Quantification of tissue shrinkage due to formalin fixation of entire post-mortem human brain | |
| Tobias Streubel1, Francisco Javier Fritz1, Herbert Mushumba2, Klaus Püschel2, and Siawoosh Mohammadi1 | ||
1Institute for Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 2Institute of Legal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany |
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This work investigates tissue shrinkage during fixation and how it is related to associated changes in three quantitative MRI parameters (longitudinal relaxation $$$R_1$$$ and effective transverse relaxation $$$R_2^*$$$ rates, and magnetization transfer saturation rate MT). We proposed a new model to estimate tissue shrinkage from brain volume changes and found that shrinkage was $$$7.7\%$$$. No apparent relation between changes in MT and tissue shrinkage were found, whereas it was remarkable for $$$R_1$$$ and $$$R_2^*$$$, indicating that mostly the extra-axonal space is reduced during fixation. |
| 3163 | Simulating the effect of axonal dispersion and noise on anisotropic R2* relaxometry in white matter | |
| Francisco Javier Fritz1, Luke J. Edwards2, Tobias Streubel1,2, Kerrin J. Pine2, Nikolaus Weiskopf2, and Siawoosh Mohammadi1,2 | ||
1Institute of System Neuroscience, Universitätklinikum Hamburg-Eppendorf, Hamburg, Germany, 2Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany |
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We introduced a forward model to simulate the effect of fibre dispersion on the angle-dependent GRE signal decay in different SNR conditions. We compared the classical signal model against three variations of the signal model derived from a second-order Taylor expansion in time of Wharton and Bowtell’s HCFM model, including a new model that accounts for fibre dispersion. We found a noise enhancement in the model parameters when using the second-order models. Moreover, we found that the orientation dependency of the GRE signal diminished for high dispersions. |
| 3164 | The effect of noise on myelin assessment by multi-exponential fitting for varying white matter fibre geometries | |
| Tonima S Ali1, Vaibhavi S Itkyal1,2, Kiran Thapaliya1,3, and Markus Barth1,2,3 | ||
1University of Queensland, Brisbane, Australia, 2Indian Institute of Technology, Madras, India, 3Griffith University, Gold Coast, Australia |
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The use of multi-echo gradient echo (mGRE) with signal compartment modelling is an increasingly popular choice for myelin assessment by measuring myelin T2* (T2*My), myelin water fraction (MWF) and g-ratio. In this simulation study, we show the effects of varying white matter microstructure and noise levels on GRE and the efficiency of commonly used fitting algorithms for predicting the true T2*My, MWF and g-ratio. |
| 3165 | A stability study of breath-hold and free-breathing liver fat and R2* quantification at 1.5T and 3T | |
| Chang Gao1,2,3, Peng Hu1,2, Brian Dale4, Marcel D. Nickel5, Stephan A.R. Kannengiesser5, Berthold Kiefer5, Vibhas Deshpande6, and Xiaodong Zhong3 | ||
1Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, United States, 2Physics and Biology in Medicine Inter-departmental Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, CA, United States, 3MR R&D Collaborations, Siemens Healthcare, Los Angeles, CA, United States, 4MR Training, Siemens Healthcare, Cary, NC, United States, 5MR Application Development, Siemens Healthcare GmbH, Erlangen, Germany, 6MR R&D Collaborations, Siemens Healthcare, Austin, TX, United States |
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Accurate quantification of proton-density fat fraction (PDFF) and R2* requires appropriate compensation of various confounding factors. A stability study was performed to investigate the impacts of different protocols and imaging parameters using both breath-hold Cartesian and free breathing radial sequences on a standardized phantom and a group of 5 same normal subjects at both 1.5T and 3T. This study revealed that flip angle, TE mode and coil usage were important protocol parameters to investigate further in larger patient population. |
| 3166 | Quality assurance of multiparametric mri protocol for multi-centre prostate cancer sequential imaging clinical trial | |
| Yu-Feng Wang1,2, Gary Liney2,3, Robba Rai2,3, Sirisha Tadimalla1, Jonathan Goodwin4, Lois Holloway2,3, and Annette Haworth1 | ||
1Institute of Medical Physics, The University of Sydney, Camperdown, Australia, 2Ingham Institute for Applied Medical Research, Liverpool, Australia, 3Liverpool and Macarthur Cancer Therapy Centre, Liverpool Hospital, Liverpool, Australia, 4Radiation Oncology Department, Calvary Mater Newcastle, Newcastle, Australia |
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Inter-/intra-scanner differences contribute to uncertainties in results from multi-centre longitudinal imaging studies. The Sequential Imaging Biofocussed Radiotherapy (SI-BiRT) trial is a multi-centre longitudinal imaging clinical trial that aims to develop imaging biomarkers using mpMRI to predict radiation therapy response in prostate cancer. Here we quantify the inter-/intra-scanner variabilities in the mpMRI protocol and scanners used in the SI-BiRT trial using commercial phantoms. ADC measurements were highly accurate while VFA T1 mapping overestimated reference values. ADC and T1 showed high intra-scanner reproducibility while R2* showed higher variability. The quantified uncertainties will be considered when interpreting results from the SI-BiRT trial. |
| 3167 | Assessment of the sensitivity of inhomogeneous Magnetization Transfer (ihMT) brain imaging with B1+ variations at 3T | |
| Lucas Soustelle1,2, Samira Mchinda1,2, Thomas Troalen3, Maxime Guye1,2, Jean-Philippe Ranjeva1,2, Gopal Varma4, David C Alsop4, Guillaume Duhamel1,2, and Olivier M Girard1,2 | ||
1Aix-Marseille Univ, CNRS, CRMBM, Marseille, France, 2APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France, 3Siemens Healthcare SAS, Saint-Denis, France, 4Division of MR Research, Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States |
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Inhomogeneous Magnetization Transfer (ihMT) is a novel myelin imaging technique. As for many other MRI techniques special attention must be paid to local B1+ variations in applications at high field. In this work, a detailed analysis of the ihMT ratio sensitivity to B1+ inhomogeneities is performed in the context of human brain imaging at 3T. It is shown that concentrating RF power is an efficient way to reduce B1+ induced bias and that the overall performance of the technique lies on a tradeoff between high ihMT ratios (sensitivity) and reduced sensitivity to B1+ inhomogeneities. |
| 3168 | Quantitative Estimation of Visual Sensitivity to Early Pathological Changes in T2-Weighted Images | |
| Chen Solomon1, Tamar Blumenfeld-Katzir1, Moti Salti2,3, Dvir Radunsky1, Noam Omer1, Neta Stern1, and Noam Ben-Eliezer1,4,5 | ||
1Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel, 2Brain Imaging Research Center (BIRC), Soroka Medical Center, Beer Sheva, Israel, 3Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer Sheva, Israel, 4Center for Advanced Imaging Innovation and Research (CAI2R), New-York University Langone Medical Center, New York, New York, NY, United States, 5Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel |
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Quantitative MRI (qMRI) may provide higher sensitivity to early pathological changes than standard qualitative assessment. This advantage, however, is yet to be rigorously compared with conventional diagnostic methods. This study aims to quantify the human ability to detect predefined changes in T2-weighted images as part of the diagnostic process of multiple sclerosis (MS). A visual diagnostic test was performed on neurosciences students, suggesting that the human vision has lower sensitivity to subtle MS lesions in T2-weighted images, in comparison to quantitative assessment of the change in T2 values. |
| 3169 | Exploring the anatomical variability in the precision of frequency difference mapping in the corpus callosum at 7T | |
| Chiara Casella1, Elena Kleban1, and Derek K Jones1 | ||
1Department of Psychology, Cardiff University Brain Research Imaging Centre, Cardiff, United Kingdom |
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We explored the anatomical variability in reliability of complex mGRE signal, and of parameters estimated by modelling this signal as a superposition of complex myelin, intra- and extra-axonal water signals, in the corpus callosum at 7T. Our data showed to be repeatable in the posterior portion of the corpus callosum, while reliability was lower in more anterior portions. These findings have important implications and need to be considered when investigating callosal microstructure with mGRE in health and disease. |
| 3170 | A method to remove the influence of fixative concentration on post-mortem T2 maps using a kinetic-tensor model | |
| Feng Qi1, Karla Miller1, Sean Foxley2, Menuka Pallebage-Gamarallage3, Ricarda AL Menke1, Olaf Ansorge3, Samuel A Hurley4, and Benjamin C Tendler1 | ||
1Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 2Department of Radiology, University of Chicago, Chicago, IL, United States, 3Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 4School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States |
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Postmortem imaging allows for validation of the origins of image contrast through comparisons with histology. However, the inclusion of formalin fixative substantially reduces the T2. This reduction is (approximately) linear with concentration. Prior to scanning, samples are often placed in a fluid that has more favourable properties for imaging (e.g. perfluorocarbon fluids). This may lead to an outflow of fixative and an increase in T2 at the tissue surface. Here we propose to correct for T2 inhomogeneity by modelling the outflow of fixative within whole, human brains using a novel kinetic tensor model, which incorporates the effects of diffusion anisotropy. |
| 3171 | Simulation of B1+ inhomogeneities errors induced on T1w/T2w contrast at 3T and 7T | |
| Mathilde Ripart1,2, Vincent Gras1, Rachida Elamrani1, Lucie Hertz-Pannier1, and Alexandre Vignaud1 | ||
1CEA, Neurospin, Université Paris-Saclay, Gif-sur-Yvette, France, 2Centrale Lyon, Ecully, France |
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The T1w/T2w ratio is commonly used at 3T as a biomarker of pathological changes in brain's structure. However, this method faces strong B1+ inhomogeneities that induce bias in the contrast. Simulations of this bias at 3T and 7T were done using an EPG model, and reported on the anatomical contours of human brains. At 3T, only a central part of the brain provides acceptable bias in the contrast (≤5%). At 7T, more than half of the brain gives unreliable contrast values. Therefore, T1w/T2w needs to be employed with cautiousness at 3T, and might not be a reliable method at 7T. |
| 3172 | Investigation on the estimation performance of phase-based T2 mapping in the presence of motion | |
| Daiki Tamada1, Xiaoke Wang1, Timothy J. Colgan1, Diego Hernando1,2, and Scott B. Reeder1,2,3,4,5 | ||
1Radiology, University of Wisconsin-Madison, Madison, WI, United States, 2Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 3Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States, 4Medicine, University of Wisconsin-Madison, Madison, WI, United States, 5Emergency Medicine, University of Wisconsin-Madison, Madison, WI, United States |
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The estimation performance of phase-based T2 mapping in the presence of motion was investigated using Bloch equation simulations. The steady-state signal of RF-phase modulated gradient echo imaging in the presence of motion was calculated. Linear, sinusoidal, and random motion were considered for the simulation. The results showed that phase errors induced by motion may lead to underestimation of T2 when using a gradient echo phase-based T2 mapping method. |
| 3173 | Reducing parameter estimate bias due to B1 field error ambiguity in CPMG MRI T2 relaxometry | |
| Nick Zafeiropoulos1, Stephen Wastling1, Mary M Reilly2, Enrico De Vita3, Tarek Yousry1, and John Thornton1 | ||
1UCL Queen Square Institute of Neurology, London, United Kingdom, 2MRC Centre for Neuromuscular Diseases, London, United Kingdom, 3King's College London, London, United Kingdom |
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B1 field deviations above and below 100% of the nominal prescribed values have been noted by previous authors as a potential source of error in MRI CPMG T2 relaxometry. We show in simulations of clinically realistic acquisition protocols that this effect causes fit instability and loss of precision, and corroborate this with in vivo lower limb muscle image data. We then introduce a B1 error polarity spatial regularization scheme, and show that this improves parameter estimation accuracy. |
| 3174 | R1 reproducibility at 3T and 7T using Bloch-Siegert based corrections for transmit field inhomogeneity | |
| Nadège Corbin1 and Martina F Callaghan1 | ||
1Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, London, United Kingdom |
||
High reproducibility of longitudinal relaxation rate (R1) estimation using the variable flip angle approach requires unbiased and precise estimation of the transmit field inhomogeneity. In this context, the Bloch-Siegert (BSS)-based B1+ mapping approaches were evaluated at 3T and 7T and compared to the SE/STE approach. R1 values in grey and white matter were slightly higher with the BSS-based techniques. At 3T, the highest reproducibility was observed with the single-echo BSS approach, using an RF spoiling increment of 90°. At 7T, the reproducibility of the techniques were equivalent in well B0-shimmed regions but diverged in regions of high B0 inhomogenity. |
| 3175 | Effect of RF Pulse Duration on Chemical Shift Encoded MRI | |
| Nathan Tibbitts Roberts1,2, Timothy Colgan1, and Scott B Reeder1,3,4,5,6 | ||
1Radiology, University of Wisconsin - Madison, Madison, WI, United States, 2Electrical and Computer Engineering, University of Wisconsin - Madison, Madison, WI, United States, 3Medical Physics, University of Wisconsin - Madison, Madison, WI, United States, 4Biomedical Engineering, University of Wisconsin - Madison, Madison, WI, United States, 5Medicine, University of Wisconsin - Madison, Madison, WI, United States, 6Emergency Medicine, University of Wisconsin - Madison, Madison, WI, United States |
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The effects of RF pulse duration on chemical shift encoded MRI (CSE-MRI) methods is a previously unexplored potential confounder for accurate and precise estimation of proton density fat fraction (PDFF) and R2*. Most signal models of CSE-MRI model RF excitation as instantaneous rotation of bulk magnetization; however, instantaneous excitation is not physically realizable. In this work we use Bloch equation simulations to characterize the effect of pulse duration on PDFF and R2* bias. We found that R2* bias was more sensitive than PDFF bias to RF pulse duration and note that clinically meaningful bias can be observed. |
| 3176 | Signal Intensity in Dentate Nucleus Does Not Always Correlate with Accumulative Gadolinium doses after Whole-Brain Radiotherapy | |
| Rongbiao Tang1, E. Mark Haacke2, Yibin Zhang2, Qingrou Wang2, Naying He2, Weibo Chen3, Ke-min Chen2, and Fuhua Yan2 | ||
1Ruijin Hospital, Shanghai, China, 2Ruijin Hosptial, Shanghai, China, 3Philips Healthcare, Shanghai, China |
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Whole-brain radiotherapy (WBRT) is often performed asynchronously with head contrast-enhanced MRI examination (CEME) in patients with brain metastasis (BM). Data regarding T1 signal intensity (SI) changes in the dentate nucleus (DN) in BM patients after WBRT and repeated exposure to gadolinium (Gd)-based contrast agents (GBCAs) are lacking. In this study, we explored the correlation between T1 SI in the DN and cumulative doses of linear GBCAs in BM patients treated with WBRT. |
| 3177 | MR signal modelling comparison and its influence on tissue parameters using gradient-echo MRI at 7 Telsa | |
| KIRAN THAPALIYA1,2, Viktor Vegh2, Steffen Bollmann2, and Markus Barth2,3 | ||
1Menzies Health Institute Queensland, Griffith University, Gold coast, Australia, 2Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia, 3School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, Australia |
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Quantitative assessment of model parameters (water fraction and frequency shift) estimated using a multi-compartment model can be useful to study tissue properties in white matter. In this work, we compared common existing complex signal models for multi-echo gradient echo data acquired at 3T and 7T. We investigate the variation of model parameters that could potentially affect different models (number of compartments and parameters) on the estimation of tissue parameters. We show that the tissue parameters vary across the sub-regions of the corpus callosum and are influenced by different modelling choices. |
| 3178 | Local Structure Orientation (LSO) for histology-based validation of MRI: evaluation in a physical phantom study | |
| Wadha Alyami1,2, Andre Kyme3, and Roger Bourne1 | ||
1Medical Imaging Sciences, Faculty of Health Sciences, University of Sydney, Sydney, Australia, 2Medical imaging sciences, King Saud University, Riyadh, Saudi Arabia, 3Biomedical Engineering, School of Aerospace Mechanical & Mechatronic Engineering, Faculty of Engineering and IT, University of Sydney, Sydney, Australia |
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Histology-based validation of magnetic resonance imaging (MRI) is essential to confirm imaging technique specificity and accuracy. One-to-one correspondence is complicated by histological preparation and differences in MRI and histology contrast mechanisms. A new approach, based on local structure orientation (LSO) and using microstructural features, is proposed. LSO facilitates registration based on direct correspondence between tissue fibre structure to emulate a common contrast mechanism. Using a physical phantom derived from a chicken heart with embedded fibrous structures, residual displacement was 14.1 mm for advanced mean squares (AMS), 2.2 mm for modified AMS (AMSR), and 3.3 mm for mutual information (MI). |
| 3179 | Current Density Measurements in the Human Brain in-vivo during TES treatment, using Multi-Band methods | |
| Munish Chauhan1, Sulagna Sahu1, Saurav Zaman Khan Sajib1, Enock Boakye1, Michael Schär2, and Rosalind J Sadleir1 | ||
1School of Biological and Health System Engineering, Arizona State University, Tempe, AZ, United States, 2Department of Radiology, Johns Hopkins University, Baltimore, MD, United States |
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Current density distribution measured in the brain can guide and verify electrical stimulation therapies. Recent studies have demonstrated current density images of human heads during TES using Magnetic Resonance Electrical Impedance Tomography (MREIT). Earlier MREIT approaches permitted imaging of three 5-mm-thick slices in a sequence lasting 6 minutes, a typical therapeutic TES administration time. MREIT sequences must be accelerated to obtain whole brain coverage. In this study, we demonstrate in-vivo use of multiband-accelerated multi-echo-gradient-echo MREIT acquisition methods to acquire 24 5-mm-thick slices over 6 minutes. Computed current density maps measured in the brain using both methods are compared. |
| 3180 | Imaging of Current Density Distribution in Deep Brain Stimulation (DBS) | |
| Munish Chauhan1, Saurav Zaman Khan Sajib1, Sulagna Sahu1, Willard S Kasoff2, and Rosalind J Sadleir1 | ||
1School of Biological and Health System Engineering, Arizona State University, Tempe, AZ, United States, 2Department of Surgery, University of Arizona, Tucson, AZ, United States |
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Computational methods have been widely used to estimate field distributions produced by conventional or recently introduced directional DBS electrodes. To date there have been no experimental measurements of fields produced by DBS. We implanted either conventional or directional DBS leads into a head-shaped homogeneous phantom filled with agar gel and compared the current densities produced by each DBS electrode type using magnetic resonance current density imaging (MRCDI). This first experimental demonstration demonstrates the expected reduced spread for directional electrodes. This approach will be used in future studies to produce detailed images of DBS fields relative to target structures. |
| 3181 | Machine learning methods applied to MR-based Electrical Properties Tomography to improve noise robustness and boundary accuracy. | |
| Adan Jafet Garcia Inda1, Shao Ying Huang2,3, Stefano Mandija4,5, and Wenwei Yu1,6 | ||
1Department of Medical Engineering, Chiba University, Chiba, Japan, 2Department of Surgery, National University of Singapore, Singapore, Singapore, 3Engineering Product Development, Singapore University of Technology and Design, Singapore, Singapore, 4Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands, 5Computational Imaging Group for MR diagnostic & therapy, University Medical Center Utrecht, Utrecht, Netherlands, 6Center for Frontier Medical Engineering, Chiba University, Chiba, Japan |
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MREPT is a technique used to non-invasively estimate the electrical properties (EPs) of tissues based on Maxwell equations from MRI measurements. However, most reconstruction techniques are susceptible to noise and have severe boundary artifacts. In this work, we designed problem-oriented machine learning methods to improve the MREPT reconstructions. Through numerical experiments with 2-D cylindrical phantoms and comparison with cr-EPT, we demonstrate the feasibility of ML approaches to provide more noise robust EPT reconstructions with lower boundary artifacts. |
| 3182 | Assessment of the sensitivity of Phase-Only Helmholtz-EPT to spatially-dependent conductivity changes using a glioma-brain-phantom | |
| Lucia Bossoni1, Andrew Webb1, Loes Huijnen2, Remco Overdevest2, and Wyger Brink1 | ||
1Leiden University Medical Center, Leiden, Netherlands, 2Leiden University, Leiden, Netherlands |
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Phase-only Helmholtz-Electrical Property Tomography (PO-HEPT) has recently shown promise for the detection and grading of diffuse glioma. However, a brain glioma is usually located away from the centre of the brain where the transceive phase and phase-only approximations used in reconstruction may not be valid. Here we assessed the sensitivity of PO-HEPT in an anatomically realistic brain phantom where an off-centre glioma-compartment was incorporated, and using a clinically applicable MR sequence. Our results show that while the accuracy of the PO-HEPT deteriorates, its sensitivity is mostly unaffected, thus allowing correlative studies of tumour grading. |
| 3183 | In Vivo Conductivity Tensor Imaging of Human Brain | |
| Nitish Katoch1, Bup Kyung Choi1, In Ok Ko2, Ji Ae Park2, Yong Soo Cho3, Jin Woong Kim3, Hyung Joong Kim1, and Eung Je Woo1 | ||
1Kyung Hee University, Seoul, Korea, Republic of, 2Korea Institute of Radiological and Medical Sciences, Seoul, Korea, Republic of, 3Chosun University Hospital and Chosun University College of Medicine, Gwangju, Korea, Republic of |
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Human brain mapping of the electrical conductivity can facilitate the understanding of brain function. The low-frequency conductivity distribution of biological tissue exhibit the anisotropic tissue property and can be expressed as tensor. Considering the most physiological events occurs in frequency below 1 kHz, we developed a new conductivity tensor imaging method which can be implemented in conventional clinical MRI scanner without using any current injections for anisotropic conductivity measurement. |
| 3184 | Conductivity Tensor Imaging (CTI): a novel contrast mechanism based on ionic conductivity for characterization of brain tumors | |
| Nitish Katoch1, Clémentine Lesbats2, Atul Singh Minhas3, Hyung Joong Kim1, Eung Je Woo1, and Harish Poptani2 | ||
1Department of Biomedical Engineering, Kyung Hee University, Seoul, Republic of Korea, 2Physiology, University of Liverpool, Liverpool, United Kingdom, 3School of Engineering, Macquarie University, Sydney, Australia |
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Unlike the previously reported method of diffusion tensor magnetic resonance electrical impedance tomography (DT-MREIT), conductivity tensor imaging (CTI) does not require external electrodes for current injection. The low frequency conductivity (σL) value can be estimated from the high frequency conductivity (σH) measured using B1 map. The σL is influenced by cell size and density, which makes it an effective technique to characterize the cellular changes in brain tumors. Rat brain tumors were studied using 9.4 T MRI scanner using CTI protocol. Changes in ionic concentration cellular states depending on tumor growth were reflected in both high and low-frequency CTI images. |
| 3185 | In vivo pelvis conductivity mapping with a 3D patch-based convolutional neural network trained on in silico MR data | |
| Soraya Gavazzi1, Cornelis AT van den Berg1,2, Mark HF Savenije1,2, H Petra Kok3, Lukas JA Stalpers3, Jan JW Lagendijk1, Hans Crezee3, and Astrid LHMW van Lier1 | ||
1Radiotherapy Department, University Medical Center Utrecht, Utrecht, Netherlands, 2Computational Imaging Group for MR diagnostic & therapy, University Medical Center Utrecht, Utrecht, Netherlands, 3Radiation Oncology Department, Amsterdam University Medical Center, Amsterdam, Netherlands |
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Pelvis conductivity is typically reconstructed with Helmholtz-based EPT. To overcome typical limitations of Helmholtz-based EPT in this challenging body site we explored reconstructing pelvis conductivity with deep learning. A 3D patch-based convolutional neural network was trained on in silica MR data (either a full complex B1+ field or transceive phase only) with realistic noise levels. These data were related to realistic pelvic anatomies and electrical properties. Preliminary results indicate that the network retrieved anatomically-detailed conductivity maps, without a priori anatomical knowledge given in input. Quantitatively, conductivity estimates on in vivo volunteer MR data were in line with literature. |
| 3186 | Computation of H- from H+ and its application to regularization for Magnetic Resonance Electrical Properties Tomography (MREPT) | |
| Takaaki Nara1 and Motofumi Fushimi1 | ||
1Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan |
||
We derive an explicit formula to compute the negative circularly polarized component of the magnetic field, $$$H^-$$$, from the measured positively polarized component, $$$H^+$$$, for magnetic resonance electrical properties tomography (MREPT). Then, using the measured $$$H^+$$$ and the computed $$$H^-$$$, a novel regularization term for MREPT is introduced based on the $$$x$$$- and $$$y$$$-components of Ampere’s law and the $$$z$$$-component of Faraday’s law that have not been used so far for the reconstruction of EPs. This physically reasonable constraint well regularizes EPs at low convection field region. |
| 3187 | Experimental Validation of Conductivity Tensor Imaging using Giant Vesicle Suspension | |
| In Ok Ko1, Bup Kyung Choi2, Nitish Katoch2, Ji Ae Park1, Yong Soo Cho3, Jin Woong Kim3, Hyung Joong Kim2, and Eung Je Woo2 | ||
1Korea Institute of Radiological and Medical Sciences, Seoul, Korea, Republic of, 2Kyung Hee University, Seoul, Korea, Republic of, 3Chosun University Hospital and Chosun University College of Medicine, Gwangju, Korea, Republic of |
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Conductivity tensor can realize volume conductor model of brain for neuroimaging and electrical stimulation. We report validation of electrodeless conductivity tensor imaging (CTI) method [1]. From CTI imaging using giant vesicle suspension at 9.4T MRI, relative error in conductivity tensor image was found to be less than 1.7% compared with the measured values using an impedance analyzer. High- and low-frequency conductivity can quantify total and extracellular water contents, respectively, at every pixel. Their difference can quantify intracellular water content at every pixel. Current CTI method can separately quantify the contributions of ion concentrations and mobility to the conductivity tensor. |
| 3188 | Feasibility of Phase-based EPT using clinical routine sequences. | |
| Jun-Hyeong Kim1, Kyu-Jin Jung1, Mina Park2, and Dong-Hyun Kim1 | ||
1electrical electronic engineering, yonsei University, seoul, Korea, Republic of, 2Department of Radiology, Gangnam Severance Hospital, seoul, Korea, Republic of |
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In this study, we test whether the preparation pulse and compensation gradient affect B1-phase and suggested a method for merging B1-phase obtained from different pulse sequences. We also try to reconstruct conductivity with the routine of guide images for surgery which have high resolution and low SNR. |
| 3189 | Acquisition-weighted MR Current Density Imaging (AW-MRCDI) improves sensitivity and spatial resolution | |
| Cihan Göksu1,2, Lars G. Hanson1,3, Fróði Gregersen1,3,4, Klaus Scheffler2,5, and Axel Thielscher1,3 | ||
1Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Hvidovre, Denmark, 2High-Field Magnetic Resonance Center, Max-Planck-Institute for Biological Cybernetics, Tübingen, Germany, 3Center for Magnetic Resonance, DTU Health Tech, Technical University of Denmark, Kgs. Lyngby, Denmark, 4Sino-Danish Center for Education and Research, Aarhus, Denmark, 5Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany |
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Exact knowledge of currents flowing inside the human brain is important for several neuroscientific applications. MRCDI combines MR with externally injected weak currents, and uses measurements of the current-induced magnetic field to estimate spatial current distribution. The method’s accuracy highly depends on the sensitivity and spatial resolution of the field measurements. Here, we improve the currently most sensitive MRCDI method based on steady-state free precession free induction decay (SSFP-FID) by using an acquisition-weighted scheme (AW-MRCDI). We compared weighted and conventional schemes by phantom experiments. AW-MRCDI demonstrated 59% increase in sensitivity and significantly improved the spatial resolution. |
| 3190 | Properties and implementation issues of phase based cr-MRECT for conductivity imaging | |
| Yusuf Ziya Ider1 and Merve Nur Akyer1 | ||
1Dept of EEE, Bilkent University, Ankara, Turkey |
||
Phase based cr-MRECT aims at reconstructing tissue conductivity without boundary artefacts. In this work some properties and implementation issues of the Phase based cr-MRECT are studied, namely, discretization methods, ill conditioning, bias due to neglecting the gradient of abs(B1+), and regularization. It is shown that by properly weighing the regularising artificial diffusion, bias-correction, and the convection term, artefact free and accurate conductivity images can be obtained. The system matrices are shown to be relatively well-conditioned and that there is no need to specify Dirichlet boundary conditions. |
| 3191 | Noniterative Electrical Properties Tomography Reconstruction Method Based on Three-Dimensional Integral Equation for the Electric Field | |
| Naohiro Eda1, Motofumi Fushimi1, Keisuke Hasegawa1, and Takaaki Nara1 | ||
1The University of Tokyo, Tokyo, Japan |
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This paper proposes a novel, noniterative reconstruction method for magnetic resonance electrical properties tomography (MREPT). For this method, we first estimate the electric field using a novel, three-dimensional integral equation, derived from Maxwell's equations and vector calculus identities. The EPs are then reconstructed from the estimated electric field, using Ampere’s law. Our method can estimate an arbitrary three-dimensional distribution of EPs, including those varying in the z-axis. The efficacy of our proposed method was validated through numerical simulations and a phantom experiment. |
| 3192 | An in-vivo study to provide reference conductivity values of the human brain at 3T | |
| Stefano Mandija1,2, Petar Petrov3, Jord Vink3, Sebastian Neggers3, and Cornelis A.T. van den Berg1,2 | ||
1Computational Imaging Group for MR diagnostic and therapy, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands, 2Department of Radiotherapy, Division of Imaging and Oncology, University Medical Center Utrecht, Utrecht, Netherlands, 3Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, Netherlands |
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First in-vivo brain conductivity reconstructions have been recently published. However, a large variation in the reconstructed conductivity values is reported and these results substantially differ from ex-vivo measurements. Given this lack of agreement, we performed an in-vivo study on eight healthy subjects to provide reference brain conductivity values. The measured in-vivo mean WM and GM conductivity values verify for the first time the literature values measured ex-vivo, while the reconstruction accuracy was verified in simulation settings. The presented values can therefore be used as a verified in-vivo reference for future studies, where new reconstruction algorithms are tested in-vivo. |
| 3193 | On the usage of deep neural networks as a tensor-to-tensor translation between MR measurements and electrical properties | |
| Ilias Giannakopoulos1,2, José Serallés2, Georgy Guryev1,2, Luca Daniel2, Elfar Adalsteinsson2,3, Lawrence Wald4,5,6, Daniel Sodickson7,8,9, Jacob White2, and Riccardo Lattanzi7,8,9 | ||
1Skoltech Center for Computational and Data-Intensive Science and Engineering, Skolkovo Institute of Science and Technology, Moscow, Russian Federation, 2Department of Electrical Engineering & Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States, 3Institute for Medical Engineering and Science, Cambridge, MA, United States, 4Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 5Department of Radiology, Harvard Medical School, Boston, MA, United States, 6Harvard-MIT Health Sciences and Technology, Cambridge, MA, United States, 7Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University School of Medicine, New York, NY, United States, 8The Bernard and Irene Schwartz Center for Biomedical Imaging (CBI), Department of Radiology, New York University School of Medicine, New York, NY, United States, 9Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States |
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Electrical properties (EP) can be retrieved from magnetic resonance measurements. We employed numerical simulations to investigate the use of convolutional neural networks (CNN) as a tensor-to-tensor translation between transmit magnetic field pattern ($$$b_1^+$$$) and EP distribution for simple tissue-mimicking phantoms. Given the volumetric nature of the problem, we chose a 3D UNET and trained the network on $$$10000$$$ data. We investigated on the usage of regularization to account for overfitting and observed that multiple dropouts through the layers of the network yield optimal EP reconstructions for $$$1000$$$ testing data. |
| 3194 | Feasibility of magnetic resonance based electrical properties tomography with deep learned reconstruction based denoising | |
| Ho-Joon Lee1, Yeonah Kang1, Marc Lebel2, Joon-Hyeong Kim3, Dong-Hyun Kim3, and Sung-Min Gho4 | ||
1Department of Radiology, Haeundae Paik Hospital, Busan, Republic of Korea, 2MR Collaboration and Development, GE Healthcare, Calagary, AB, Canada, 3Department of Electrical and Electronic Engineering, Yonsei University, Seoul, Republic of Korea, 4MR Collaboration and Development, GE Healthcare, Seoul, Republic of Korea |
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With advances in deep learning, feasibility has been investigated for MREPT reconstruction showing interesting results. However whether images denoised with deep learned reconstruction will improve EPT map quality has not been investigated. After denoising of complex data acquired with a DL algorithm, EPT maps were generated with phase based 2D-weighted polynomial fitting. Use of DL, shows better results as compared to conventionally generated maps (i.e. decreased NRMSE, increased PSNR and SSIM, with increasing denoising levels), and results in sharper appearing maps. Spreading of boundary artifacts are not observed with increasing denoising factors. |
| 3195 | How to train a Deep Convolutional Neural Network for Quantitative Susceptibility Mapping (QSM) | |
| Thomas Jochmann1, Jens Haueisen1, and Ferdinand Schweser2,3 | ||
1Department of Computer Science and Automation, Technische Universität Ilmenau, Ilmenau, Germany, 2Buffalo Neuroimaging Analysis Center, Dept. of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, United States, 3Center for Biomedical Imaging, Clinical and Translational Science Institute, University at Buffalo, The State University of New York, Buffalo, NY, United States |
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Deep convolutional neural networks have recently gained popularity for solving the ill-posed dipole inversion problem in Quantitative Susceptibility Mapping (QSM). The training of the neural networks is performed with examples of χ and f that can either be obtained from physical simulations on synthetic source distributions, or through “classical” QSM methods on real data. For both choices, there is a plethora of decisions to make and parameters to set. Here we seek to present best practices regarding the modelling of synthetic source distributions and data augmentation. |
| 3196 | SOJU-Net—Denoising MR phase images with physics-informed deep learning using artificial Rician noise augmentation | |
| Thomas Jochmann1, Nora Kuechler1, Jens Haueisen1, and Ferdinand Schweser2,3 | ||
1Department of Computer Science and Automation, Technische Universität Ilmenau, Ilmenau, Germany, 2Buffalo Neuroimaging Analysis Center, Dept. of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, United States, 3Center for Biomedical Imaging, Clinical and Translational Science Institute, University at Buffalo, The State University of New York, Buffalo, NY, United States |
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Phase noise follows the Rician distribution, with a non-linear dependency of the phase noise on the local magnitude signal intensity. In this work, we present SOJU-Net, a deep-learning based denoising for MR phase images. SOJU-Net reduces Rician noise while preserving boundary contrast. |
| 3197 | Sharper Images in Quantitative Susceptibility Mapping with Magnetometric Dipole Kernels | |
| Anders Dyhr Sandgaard1 and Sune Nørhøj Jespersen1,2 | ||
1Center for Funcionally Integrative Neuroscience, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark, 2Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark |
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The purpose of this study is to consider the GRE signal phase in a voxel for short echo times, from an MRI-visible fluid induced by MRI-invisible magnetic inclusions. We find that the signal phase relates to the magnetometric demagnetization field. In Fourier space, this defines a magnetometric dipole kernel which can be used to perform QSM. Using the data from the 2016 QSM challenge, we show that applying the magnetometric dipole kernel increases the sharpness, and that it is possible to increase the sharpness of already made STI susceptibility maps. |
| 3198 | ProxVNET: A proximal gradient descent-based deep learning model for dipole inversion in susceptibility mapping | |
| Christian Kames1,2, Jonathan Doucette1,2, and Alexander Rauscher1,2,3 | ||
1Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada, 2UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada, 3Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada |
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A deep learning model, ProxVNET, is proposed to solve the ill-posed dipole inversion in susceptibily mapping. ProxVNET is derived from unrolled proximal gradient descent iterations wherein the proximal operator is implemented as a V-Net and is itself learned. ProxVNET is shown to outperform the U-Net-based dipole inversion deep learning model QSMnet when compared to COSMOS reconstructed susceptibility maps. |
| 3199 | Recovering phase from homodyne filtered phase data using a residual dense network | |
| Christian Kames1,2, Jonathan Doucette1,2, and Alexander Rauscher1,2,3 | ||
1Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada, 2UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada, 3Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada |
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In this work we train a residual dense network to recover homodyne filtered phase data. The proposed approach is able to accurately recover phase information. Susceptibility maps computed from the recovered phase yield the same accuracy as susceptibility maps computed from the original phase when compared to COSMOS. |
| 3200 | Improved signal modeling in Quantitative Susceptibility Mapping using multi-echo complex Total Field Inversion (mcTFI) | |
| Yan Wen1,2, Thanh Nguyen2, Junghun Cho2,3, Pascal Spincemaille2, and Yi Wang3,4 | ||
1Meinig School of Biomedical Engineering, Cornell University, new york, NY, United States, 2Radiology, Weill Cornell Medicine, New York, NY, United States, 3Meinig School of Biomedical Engineering, Cornell University, New York, NY, United States, 4Radiology, Weill Cornell Medicine, new york, NY, United States |
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Multi-echo Complex Total Field Inversion (mcTFI) is a Total Field Inversion (TFI) method that computes QSM directly from the complex gradient echo data, for which the assumption of Gaussian noise is well justified. mcTFI demonstrated improvement over TFI in simulation and hemorrhage brain. |
| 3201 | Improved Susceptibility Weighted Imaging using bipolar multi-echo acquisition and optimized processing of phase and magnitude data: CLEAR-SWI | |
| Simon Daniel Robinson1,2,3, Gilbert Hangel2, Beata Bachrata2, Andreas Ehrmann2, Siegfried Trattnig2, Christian Enzinger3, Markus Barth1, and Korbinian Eckstein2 | ||
1Centre for Advanced Imaging, University of Queensland, Brisbane, Australia, 2Medical University of Vienna, Vienna, Austria, 3Medical University of Graz, Graz, Austria |
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We describe a systematic optimization of gradient-echo-based SWI at 7T, encompassing SNR in single-echo vs multi-echo acquisitions (both monopolar and bipolar), coil combination, phase unwrapping, filtering, echo weighting and correction of image inhomogeneity. The improvement achieved with the resulting Contrast-weighted, Laplace-unwrapped, bipolar multi-Echo, ASPIRE-combined, homogeneous, improved Resolution SWI (or CLEAR-SWI) is compared to ‘Standard’ single-echo, Homodyne filtered SWI in healthy subjects and patients. CLEAR-SWI reduces signal dropout, eliminates wrap artefacts and provides multi-echo phase and magnitude data for R2* mapping and QSM. Applied clinically, it provides improved visibility of multiple sclerosis lesions and the composition of tumors. |
| 3202 | U3-Net for Deep Vector QSM – Solving the Susceptibility Tensor Phase Model in Single-Orientation MRI | |
| Edith Franziska Baader1, Thomas Jochmann2, Jens Haueisen2, Robert Zivadinov1,3, and Ferdinand Schweser1,3 | ||
1Buffalo Neuroimaging Analysis Center, Department of Neurology at the Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, United States, 2Department of Computer Science and Automation, Technische Universität Ilmenau, Ilmenau, Germany, 3Center for Biomedical Imaging, Clinical and Translational Science Institute, University at Buffalo, The State University of New York, Buffalo, NY, United States |
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Quantitative susceptibility mapping (QSM) is increasingly being used to study the brain iron homeostasis and white matter pathology. However, all QSM algorithms that are currently used in the clinical setting use a physical model that neglects the well-established anisotropic magnetic susceptibility of myelin. In this work, we demonstrate that an extended U-Net allows solving a Vector QSM model that accounts for field perturbations caused by off-diagonal tensor elements. The proposed Deep Vector QSM yielded improved estimates of χ33 compared to conventional QSM. |
| 3203 | TFIR - A Spatial Frequency and R2* Informed Regularization for Total Field Inversion in Quantitative Susceptibility Mapping. | |
| Priya S Balasubramanian1, Lingfei Guo2, Weiyuan Huang2, Pascal Spincemaille3, and Yi Wang4 | ||
1Electrical and Computer Engineering, Cornell University, Ithaca, NY, United States, 2Weill Cornell, Cornell University, New York, NY, United States, 3Weill Cornell, Cornell University, New York City, NY, United States, 4Biomedical Engineering, Cornell University, New York, NY, United States |
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TFIR is a novel regularization framework for total field quantitative susceptibility mapping. This method employs spatial frequency selection and R2* information within the L2 regularization method to map field to susceptibility source. It outperforms local field methods and existing regularization frameworks for total field susceptibility mapping, such as LN-QSM when computing error with respect to COSMOS and numerical and gadolinium phantoms. Hemorrhage cases and non-hemorrhage in vivo cases have reduced streaking and shadowing artifacts when reconstructed using TFIR compared to PDF-MEDI-SMV and LN-QSM. Future directions include spatial frequency selection automation in order to produce optimal signal to noise and accuracy. |
| 3204 | Phantom Validation of Simultaneous Mapping of PDFF, R2*, and Susceptibility | |
| Collin J Buelo1,2, Ruiyang Zhao1,2, Ante Zhu2,3, Scott B. Reeder1,2,3,4,5, and Diego Hernando1,2,3 | ||
1Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 2Radiology, University of Wisconsin-Madison, Madison, WI, United States, 3Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States, 4Medicine, University of Wisconsin-Madison, Madison, WI, United States, 5Emergency Medicine, University of Wisconsin-Madison, Madison, WI, United States |
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Chemical shift-encoded (CSE) MRI can be used to simultaneously obtain multi-parametric maps, including R2*, proton density fat fraction (PDFF), and tissue susceptibility, to aid in the diagnosis of diffuse liver disease. However, the presence of fat in tissue can confound both R2* and B0 field estimation and consequently quantitative susceptibility mapping (QSM). To validate this multi-parametric mapping, comparison of quantitative maps to phantoms with known iron concentrations were performed. This work demonstrated the feasibility of accurate PDFF mapping, and R2* and susceptibility measurements that are linearly dependent on both iron and fat concentration. |
| 3205 | Hybrid Data fidelity term approach for Quantitative Susceptibility Mapping | |
| Mathias Lambert1,2,3, Carlos Milovic1,2,3, and Cristián Tejos1,2,3 | ||
1Department of Electrical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile, 2Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Santiago, Chile, 3Millennium Nucleus for Cardiovascular Magnetic Resonance, Santiago, Chile |
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Here we present the winner of the QSM challenge 2.0 in the RMS category, a novel hybrid data consistency method. We validated our method with in vivo data. |
| 3206 | Can Multi-Parametric Mapping Sequences Be Used for Accurate Quantitative Susceptibility Mapping? | |
| Russell Murdoch1, Jamie Kawadler2, David Carmichael2,3, Fenella Kirkham2, and Karin Shmueli1 | ||
1Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, 2Great Ormond Street Institute of Child Health, University College London, London, United Kingdom, 3Biomedical Engineering & Imaging Sciences, King's College London, London, United Kingdom |
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We compared the results of Quantitative Susceptibility Mapping (QSM) in each of the Proton Density (PD-), Magnetization Transfer (MT-) and T1-weighted Multi-Echo Gradient-Echo (ME-GRE) sequences in Multi-Parametric Mapping (MPM) with QSM from a conventional ME-GRE sequence. In deep grey matter (GM) regions, we found significant susceptibility (χ) correlations between each sequence pair. Correlation coefficients were lower in white matter (WM), particularly in T1-w and MT-w sequences. Averaging χ over MPM sequences increased correlations in WM and reduced noise in GM and WM. Whole-brain χ difference maps showed the largest χ differences in and around large veins and air spaces. |
| 3207 | Simultaneous T1-weighted imaging, R2* mapping, and QSM from a multi-echo MPRAGE sequence using a radial fan-beam sampling scheme at 3 Tesla | |
| Hongfu Sun1, M. Ethan MacDonald2, R. Marc Lebel3, and G. Bruce Pike2 | ||
1University of Queensland, Brisbane, Australia, 2University of Calgary, Calgary, AB, Canada, 3General Electric Healthcare, Calgary, AB, Canada |
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A multi-echo MPRAGE sequence with radial fan-beam segments is demonstrated at 3 T. The radial fan-beam sampling scheme permits any number of encoding steps by adjusting the fan size for each inversion segment, which allows longer echo time for magnetic susceptibility contrast. Simultaneous T1-weighted image, R2* map, and QSM were successfully extracted from the single acquisition and were compared with images reconstructed from standard single-echo MPRAGE and multi-echo GRE acquisitions. |
| 3208 | Use of high-resolution QSM to identify global patterns in the ex vivo human brain cortex at 7T | |
| Leah Morgan1, Berkin Bilgic1, Andre van der Kouwe1,2, Jean Augustinack1,2, Jonathan Polimeni2,3, Anna Blazejewska1,2, Viviana Siless1,2, Allison Stevens1, Bram R Diamond1, Natalya Slepneva1, Bruce Fischl1, and Divya Varadarajan1 | ||
1A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, 2Harvard Medical School, Cambridge, MA, United States, 3Harvard-MIT Division of Health Sciences and Technology, Boston, MA, United States |
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Quantitative susceptibility mapping (QSM) can reflect the iron and myelin concentration within human brain tissue. Ex vivo MRI can allow us to study the cortical laminar structure at high-resolution. Here we conduct a study to combine the two, that is to analyze QSM maps of an ex vivo human brain cortex at 500um and 150um resolution. Our analysis shows matching global patterns of positive susceptibility at the gray-white boundary for both resolutions that were validated with iron-stain on a tissue-block. We find visual cortex, and localized regions of parietal and frontal lobe to contain the highest concentration of positive susceptibility. |
| 3209 | Highly Accelerated Compressed-Sensing-Based Field-mapping is Possible for Body QSM Applications | |
| Christof Böhm1, Julio Oscanoa1,2, Sophia Kronthaler1, Maximilian N. Diefenbach1,3, Alexandra Gersing1, Jakob Meineke4, and Dimitrios C. Karampinos1 | ||
1TUM, Munich, Germany, 2Stanford University, Stanford, CA, United States, 3Division of Infectious Diseases and Tropical Medicine, University Hospital, LMU, Munich, Germany, 4Philips Research, Hamburg, Germany |
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Body QSM relies on accurate magnetic field-mapping that particularly accounts for the presence of fat. Due to the need to account for T2* effects and perform water–fat separation, water–fat-imaging-based field-mapping typically acquires multiple echoes with appropriate echo time step, increasing the total required scan time especially for high-resolution body QSM. To reduce scan time, several acceleration schemes have been proposed, such as parallel imaging and compressed sensing (CS). This work demonstrates the feasibility of high CS acceleration factors to distinguish strong para- and diamagnetic susceptibility sources in body regions with CS acceleration factors of 10 and higher. |
| 3210 | Ultrashort Echo Time Quantitative Susceptibility Mapping (UTE-QSM) as a Highly Sensitive Biomarker for Hemophilic Arthropathy | |
| Hyungseok Jang1, Annette von Drygalski1, Xing Lu1, Yajun Ma1, Srila Gopal1, Jiang Du1, and Eric Chang1,2 | ||
1University of California, San Diego, San Diego, CA, United States, 2VA San Diego Healthcare System, San Diego, CA, United States |
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Hemophilia is a genetic bleeding disorder afflicting about 20,000 people in the US and over 400,000 people in the world. Severe hemophilia is characterized by frequent joint bleeding, resulting in debilitating arthropathy because of toxic iron depositions (e.g., hemosiderin) in synovium and cartilage. Development of a sensitive, non-invasive biomarker is of high importance to determine efficacy of costly treatment plans. In this study, we investigate the feasibility of ultrashort echo time-based QSM (UTE-QSM) to identify hemosiderin deposition and to provide a sensitive biomarker for joint disease in hemophilia. |
| 3211 | Quantitative susceptibility mapping and PET indicate iron-related cognitive decline during aging | |
| Lin Chen1,2,3, Anja Soldan4, Kenichi Oishi1, Andreia Faria1, Marilyn Albert4, Peter C.M. Van zijl1,2, and Xu Li1,2 | ||
1Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD, United States, 2F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, 3Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, XIAMEN, China, 4Department of Neurology, Johns Hopkins University, Baltimore, MD, United States |
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We investigated the associations between brain iron levels, as measured by QSM MRI, and amyloid-β plaque load as measured by 11C-PiB PET imaging, and their possible synergistic effect on both global composite and domain specific cognitive functions, including memory, visuospatial processing and language. Various association patterns were observed between iron load and amyloid-β deposition in voxel-based analysis. More importantly, in cognitively normal adults, iron levels in several brain regions were found negatively associated with cognition. This was independent of amyloid-β load, suggesting that the impact of iron on cognition may be related to other known molecular changes during early aging. |
| 3212 | Sampling and Modeling UTE Signals is Important to Estimate Bone Marrow Susceptibility | |
| Christof Böhm1, Sophia Kronthaler1, Maximilian N. Diefenbach1,2, Jakob Meineke3, and Dimitrios C. Karampinos1 | ||
1TUM, Munich, Germany, 2Division of Infectious Diseases and Tropical Medicine, University Hospital, LMU, Division, Munich, Germany, 3Philips Research, Hamburg, Germany |
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Body QSM relies on accurate magnetic field-mapping. A well-established water–fat voxel signal model with shared $$$R_2^*$$$ has successfully been used for body QSM based on multi-echo data at conventional echo times. However, when UTE echoes are recorded to obtain field-map information in previously unavailable MR signal voids, such as trabecular bone, the above water–fat model is no longer accurate. Therefore a joint 2-signal-model fitting using graph-cuts is proposed and applied. Further, this work demonstrates the importance of UTE echoes to obtain correct susceptibility values of cortical bone and more importantly, for bone marrow. |
| 3213 | Increased susceptibility in cortical veins and nuclei in small vessel disease revealed by susceptibility weighted imaging and mapping at 7T | |
| Yue Wu1,2,3, Qingle Kong1,2,3, Chen Ling4, Chengyue Sun4, Jing An5, Rong Xue1,2,3, Yan Zhuo1,2,3, Qi Yang6, Yun Yuan4, and Zihao Zhang1,2,3 | ||
1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, 2University of Chinese Academy of Sciences, Beijing, China, 3CAS Center for Excellence in Brain Science and Intelligence Technology, Beijing, China, 4Department of Neurology, Peking University First Hospital, Beijing, China, 5Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China, 6Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China |
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Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary cerebral small vessel disease (SVD). This study aimed to use susceptibility weighted imaging and mapping (SWIM) at 7 Tesla to evaluate venous oxygen saturation (SvO2) and subcortical nuclear iron deposition and explore the correlation of these parameters with the clinical phenotypes of CADASIL patients. We found decreases in SvO2 and abnormal iron deposition in patients compared with healthy individuals. Also, we found associations between susceptibilities and clinical characteristics of CADASIL. These results suggest that SWIM can be used to assess clinical conditions of SVD patients. |
| 3214 | Sensitivity of Quantitative Susceptibility Mapping to Temperature: A Phantom Study | |
| Hirohito Kan1,2, Yuto Uchida3,4, Masahiro Takizawa5, Tosiaki Miyati6, Hiroshi Kunitomo7, Nobuyuki Arai7, Harumasa Kasai7, and Yuta Shibamoto2 | ||
1Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya City, Japan, 2Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya City, Japan, 3Department of Neurology, Nagoya City University Graduate School of Medical Sciences, Nagoya City, Japan, 4Department of Neurology, Toyokawa City Hospital, Toyokawa, Japan, 5Healthcare Business Unit, Hitachi, Ltd., Tokyo, Japan, 6Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan, 7Department of Radiology, Nagoya City University Hospital, Nagoya City, Japan |
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To date, we are unaware of any reports regarding quantitative susceptibility mapping (QSM) at different temperatures. To clarify the temperature dependence of susceptibility estimated by QSM analysis, we investigated the relationships between temperature and susceptibility using a simple cylinder phantom with varying temperatures. This study has demonstrated that a significant inverse correlation was found between the temperature and the susceptibility value estimated by QSM analysis. This dependence might be the confounding factor of QSM-based iron estimation. |
| 3215 | 3D Texture Analysis of Quantitative Susceptibility Mapping distinguishes Anaplastic Astrocytoma from Glioblastoma | |
| Jinwei Zhang1, Shun Zhang2, Hersh Patel3, Jacquelyn Knapp4, Gloria Chiang2, David Pisapia2, John Tsiouris2, Linda Heier2, Pascal Spincemaille2, Thanh Nguyen2, Yi Wang2, and Ilhami Kovanlikaya2 | ||
1Biomedical Engineering, Cornell University, Ithaca, NY, United States, 2Radiology, Weill Cornell Medical College, New York, NY, United States, 3New York Presbyterian Hospital, New York, NY, United States, 4Cornell University, New York, NY, United States |
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3D texture analysis-based feature extraction was deployed on QSM images of malignant astrocytoma (Anaplastic Astrocytoma (AA), grade III and Glioblastoma (GB), grade IV) and support vector classifier (SVC) (1) was trained and tested on multiple training-test dataset splits with different numbers of selected features using cross-validation (CV). Experiments indicate texture analysis on QSM is useful for differentiating AA and GB with high accuracy (94.7%). |
| 3216 | The effect of voxel size on magnetic susceptibility and R2* of intramyocardial hemorrhage at 3 and 7 T | |
| Brianna F. Moon1, Srikant Kamesh Iyer2, Nicholas J. Josselyn2, James J. Pilla2, Joseph H. Gorman III3, Robert C. Gorman3, Cory Tschabrunn4, Giovanni Ferrari5, Yuchi Han4, Harold I. Litt2, and Walter R. Witschey2 | ||
1Bioengineering, University of Pennsylvania, Philadelphia, PA, United States, 2Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 3Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 4Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 5Surgery, Columbia University Irving Medical Center, New York City, NY, United States |
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Intramyocardial hemorrhage is a complication of reperfused myocardial infarction. Quantitative susceptibility mapping (QSM), R2*-mapping and T2*-weighted images provide quantitative assessment and image contrast based on the presence of iron. We sought to determine the relationship between magnetic susceptibility and R2* with varying voxel size at 3 and 7 T, where tissue magnetic susceptibility showed independence of field strength but dependence on voxel size. At high resolution the detection of heterogeneous infarct magnetic susceptibility improved in a large animal model of myocardial infarction. |
| 3217 | Comparison of Background Field Removal Strategies in Joint Quantitative Susceptibility Mapping in Abdomen | |
| Julia Velikina1, Ante V Zhu2,3, Collin V Buelo1,4, Jing Zhou5, Timothy J Colgan2, Kritisha Rajlawot5, Bingjun He5, Jin Wang5, Scott B Reeder1,3,4,6,7, Alexey Samsonov4, and Diego Hernando1,2,3 | ||
1Medical Physics, University of Wisconsin, Madison, WI, United States, 2Radiology, University of Wisconsin - Madison, Madison, WI, United States, 3Biomedical Engineering, University of Wisconsin - Madison, Madison, WI, United States, 4Radiology, University of Wisconsin, Madison, WI, United States, 5Sun Yat-sen University, Guangzhou, China, 6Medicine, University of Wisconsin - Madison, Madison, WI, United States, 7Emergency Medicine, University of Wisconsin - Madison, Madison, WI, United States |
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Quantitative susceptibility mapping (QSM) is a promising technique for direct measure of iron concentration in vivo. In abdominal imaging, QSM faces challenges of strong background field, presence of fat, complex anatomy, low image resolution, and rapid signal decay with high iron concentration. Many methods for background field removal utilize spherical mean value property of harmonic functions, resulting in straightforward approach with known limitations in accuracy and edge preservation. Here, we propose an alternative background field removal method based on direct implementation of the Laplace operator and compare its performance with spherical mean value kernels within the joint QSM estimation framework. |
| 3218 | Liver iron content measurement in living mice with quantitative susceptibility mapping | |
| Anton Abyzov1, Joao Piraquive1, Katell Peoc'h2, Philippe Garteiser1, and Bernard E. Van Beers1 | ||
1Laboratory of Imaging Biomarkers, Center of Research on Inflammation, UMR1149 Inserm-University Paris Diderot, Paris, France, 2Department of biochemistry, University Hospital Paris Nord - Beaujon, AP-HP, Clichy, France |
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To evaluate the feasibility of quantitative susceptibility mapping (QSM) in living mice liver and the robustness of QSM and transverse relaxation rate (R2*) based liver iron quantification. We show that QSM can be accurately performed in mice liver despite respiratory motion and that magnetic susceptibility measurements correlate more strongly with inductively coupled plasma mass spectrometry (ICP-MS) based iron quantification and have smaller standard deviations and narrower Bland-Altman agreement limits than R2* measurements. |
| 3219 | Using QSM to Quantify Microbubble Concentrations | |
| Barbara Dymerska1, Bernard Siow2, and Karin Shmueli1 | ||
1Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, 2Magnetic Resonance Imaging, The Francis Crick Institute, London, United Kingdom |
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Microbubbles are a well-established intravascular ultrasound contrast agent. There is increasing interest in MRI-guided microbubble-mediated focused ultrasound treatments such as thermal surgery. MRI magnitude has a non-linear and non-local dependence on microbubble size and volume fraction, making it unsuitable for estimating microbubble concentrations. Quantitative Susceptibility Mapping (QSM) is a strong candidate for tracking microbubble concentration, destruction and clearance because the susceptibility depends linearly on the volumetric bubble concentration. Here, we show the first QSM of microbubbles in a phantom and observe that the measured susceptibility has a high SNR and is directly proportional to the microbubble volumetric concentration. |
| 3220 | Application of Fourier-domain Analysis Based Unwrapping Technique in Quantitative Susceptibility Mapping (QSM) of Intracerebral Hemorrhage | |
| Ashmita De1, Hongfu Sun1, Kenneth S. Butcher2, and Alan H. Wilman1 | ||
1Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada, 2Division of Neurology, Department of Medicine, University of Alberta, Edmonton, AB, Canada |
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QSM offers a means to measure iron content changes in hemorrhage. However, the rapid T2* decay in hemorrhage causes a severe signal loss resulting in low SNR which cause failure of standard phase unwrapping in certain cases. Fourier-domain analysis based unwrapping technique may be useful to produce susceptibility maps of hemorrhages having low SNR. This method removes residual phase wraps resulting in artifact-free QSM with boundaries of the hemorrhage area more distinct to facilitate area measurement. Thus, this method can provide more precise susceptibility maps in cases where conventional unwrapping methods fail. |
| 3221 | Clinical viable QSM using accelerated, segmented 3D EPI with inline, automated QSM post-processing | |
| Monique Tourell1,2, Ashley Stewart1,2, Jin Jin2,3,4,5, Sunil Patil6, Kieran O'Brien1,2,3, Simon Robinson1,7,8, and Markus Barth1,2,5 | ||
1Centre for Advanced Imaging, University of Queensland, Brisbane, Australia, 2ARC Training Centre for Innovation in Biomedical Imaging Technology, The University of Queensland, Brisbane, Australia, 3Siemens Healthcare Pty Ltd, Brisbane, Australia, 4Mark and Mary Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, CA, United States, 5School of Information Technology and Electrical Engineering, the University of Queensland, Brisbane, Australia, 6Siemens Healthcare Pty Ltd, Malvern, PA, United States, 7High Field Magnetic Resonance Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria, 8Department of Neurology, Medical University of Graz, Graz, Austria |
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Successful translation of QSM into the clinic requires the combination of fast imaging protocols with robust, automated on-scanner processing. In this work we present clinical viable QSM: acquisition of phase data using accelerated, segmented 3D EPI in 30 seconds, and automated QSM post-processing on the scanner in under 2 minutes. The resultant susceptibility maps were of comparable quality to those obtained using a GRE sequence. Analysis of the susceptibilities measured within the caudate, putamen and pallidum demonstrates that 3D EPI with on-scanner processing produces susceptibility values in good agreement with those obtained from a GRE sequence, and offline processing pipelines. |
| 3222 | Reduced QSM values in the caudate and amygdala of first episode mania patients | |
| Vanessa Wiggermann1,2, Enedino Hernández-Torres3, Christian Kames1,2, Leonardo E daSilveira4,5, Taj Dhanoa5, Alexander Rauscher1,2, and Lakshmi N Yatham5,6 | ||
1Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada, 2Pediatrics, University of British Columbia, Vancouver, BC, Canada, 3Medicine (Neurology), University of British Columbia, Vancouver, BC, Canada, 4Laboratory of Molecular Psychiatry, Centro de Pesquisas Experimentais, Hospital de Clínicas de Porto Alegre, Porto Algre, Brazil, 5Mood Disorders Centre, University of British Columbia, Vancouver, BC, Canada, 6Psychiatry, University of British Columbia, Vancouver, BC, Canada |
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Bipolar I disorder is characterized by recurrent manic and depressive episodes. Both, dopamine and oxidative stress, resulting from mitochondrial dysfunction, have been implicated in BD and volumetric and metabolic changes have been reported. Nevertheless, it remains unknown whether changes result from treatment or ongoing disease, or if they are present at first episode mania. We used R2* and quantitative susceptibility mapping (QSM) to assess differences in brain iron and myelination in a cohort of first episode mania patients compared to controls. Patients exhibited lower QSM values than controls in the caudate and amygdala, possibly linked to iron loss or hypermyelination. |
| 3223 | Increased sensitivity for cerebral microbleed detection on SWI compared to QSM | |
| Sivakami Avadiappan1, Melanie A Morrison1, Yicheng Chen1, Angela Jakary1, Christopher P Hess1, and Janine M Lupo1 | ||
1University of California San Francisco, San Francisco, CA, United States |
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Although susceptibility weighted imaging (SWI) has been the standard method for quantifying and evaluating cerebral microbleeds, more recently total lesion susceptibility obtained from quantitative susceptibility mapping (QSM) has been found to correlate with measures of disease burden and can provide more accurate estimates of microbleed volume. This study found that 2.5 times as many CMBs can be detected on SWI compared to QSM images, with the number of CMBs missed by QSM increasing as a function of decreasing CMB size, highlighting the importance of including SWI for a more accurate assessment of disease burden in these patients. |
| 3224 | Sparsity based machine learning algorithms for oxygen extraction fraction mapping | |
| Junghun Cho1, Hae-Yeoun Lee2, jinwei Zhang1, Pascal Spincemaille3, Hang Zhang4, Simon Hubertus5, Yan Wen1, Ramin Jafari1, Shun Zhang3, Thanh Nguyen3, Ajay Gupta3, and Yi Wang1,3 | ||
1Biomedical Engineering, Cornell University, New York, NY, United States, 2Computer Software Engineering, Kumoh National Institute of Technology, Gumi, Republic of Korea, 3Radiology, Weill Cornell Medical College, New York, NY, United States, 4Electrical and Computer Engineering, Cornell University, New York, NY, United States, 5Computer Assisted Clinical Medince, Heidelberg University, Mannheim, Germany |
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In this work, dictionary and deep learning based algorithms are developed that take advantage of sparse signal representations to improve the accuracy and speed of oxygen extraction fraction (OEF) mapping based on the QSM+qBOLD (QQ) modeling of multi-echo gradient echo data without vascular challenge. The developed dictionary learning (QQ-DL) and deep neural network (QQ-NET) algorithms are significantly faster and provide more accurate OEF maps in simulation than a current algorithm based on cluster analysis of time evolution (CAT). In ischemic stroke patients, QQ-DL and QQ-NET show OEF maps that are consistent with DWI-defined lesions. |
| 3225 | Generalized methods for separating susceptibility and chemical shift/exchange | |
| Hwihun Jeong1, Hyunsung Eun1, and Jongho Lee1 | ||
1Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea |
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We proposed two generalized methods, weighted-average and least-squares methods, to separate susceptibility and chemical shift/exchange using multiple arbitrary B0 directional phase images. Compared to the previous method that requires three orthogonal directional data, the proposed methods can utilize data with smaller head rotation. A preliminary in-vivo result is presented. |
| 3226 | Semi-Supervised Image Domain Transfer for Dixon Water and Fat Separation | |
| Jong Bum Son1, Ken-Pin Hwang1, Marion E. Scoggins2, Basak E. Dogan3, Gaiane M. Rauch2, Mark D. Pagel4, and Jingfei Ma1 | ||
1Imaging Physics Department, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 2Diagnostic Radiology Department, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 3Department of Diagnostic Radiology, The University of Texas Southwestern Medical Center, Dallas, TX, United States, 4Cancer Systems Imaging Department, The University of Texas MD Anderson Cancer Center, Houston, TX, United States |
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Deep learning neural-networks for Dixon imaging require a large number of “paired” input and output images for network training. Moreover, the previous methods require Dixon images as their network input, thus they could not be used to reconstruct water images from regular T1 or T2-weighted images. In this work, we propose an image domain transfer based deep-learning network which can reconstruct water images from either T1 or T2-weighted MR images. Using semi-supervised learning, two separate groups of “unpaired and unordered” input and output images were used to translate either T1 or T2-weighted images to their corresponding water-only images. |
| 3227 | A Novel Chemical Shift-Selective Fat Saturation RF Pulse Design with Robustness to B0/B1 Inhomogeneity: A Demonstration on Breast MRI at 3T | |
| Feng Xu1,2, Wenbo Li1,2, Dapeng Liu1,2, Dan Zhu3, Kelly Myers1, Michael Shär1, and Qin Qin1,2 | ||
1The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, School of Medicine, Baltimore, MD, United States, 2F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, 3Biomedical Engineering, Johns Hopkins University, School of Medicine, Baltimore, MD, United States |
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Chemical shift-selective fat saturation (CHESS) is the most commonly used fat suppression technique for clinical MRI. Conventional Gaussian-shaped pulses are sensitive to B1 inhomogeneity and their wide transitional band can be affected by B0 off-resonance. Uniform fat saturation across a large field of view (FOV) is especially challenging for body and breast MRI at 3T. Here, we designed a novel frequency-selective RF pulse based on the optimal control theory with robustness to a targeted wide range of B0/B1 conditions. Its superior performance than the regular ones was demonstrated using T1-weighted sequences with whole-breast coverage. |
| 3228 | Multi-parametric quantification of multiple spectral components by an extended MR-STAT framework | |
| Michael A. Eijbersen1, Hongyan Liu1, Oscar van der Heide1, Cornelis A.T. van den Berg1, and Alessandro Sbrizzi1 | ||
1Computational Imaging group for MR Diagnostics and Therapy, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands |
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We present a novel method called Bicompartemental MR-STAT for simultaneous quantification T1, T2 and Proton density for two resonances based upon the MR-STAT framework. T1 and T2 may vary per compound in this framework. Additionally B0 is reconstructed by taking advantage of multple readouts within each TR which allows for separate but accurate B0 reconstruction. |
| 3229 | Optimized fast fat-fraction mapping in the knee using Signal Profile Asymmetries for Robust multi-Compartment Quantification (SPARCQ) | |
| Adèle LC Mackowiak1,2,3, Tom Hilbert3,4, Giulia MC Rossi1,3, Tobias Kober3,4, and Jessica AM Bastiaansen1 | ||
1Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, 2Department of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland, 3Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland, 4LTS5, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland |
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The Signal Profile Asymmetries for Robust multi-Compartment Quantification (SPARCQ) framework was recently developed and used to quantify water and fat content in tissues. Applying SPARCQ on bSSFP signal profiles obtained from phase-cycled acquisitions provided reliable fat fractions with a total scan time of 20:21min at low resolution. In this study, SPARCQ was accelerated and optimized for water-fat separation using numerical simulations and in vivo experiments to obtain a clinically acceptable protocol. Images and fat-fraction maps of knees at an isotropic resolution of (1.25mm)3 were obtained with a scan time of 7:12min. |
| 3230 | Multiple dual-echo reconstructions to improve the robustness of water-fat MRI | |
| Samir D. Sharma1 | ||
1Canon Medical Research USA, Mayfield Village, OH, United States |
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A challenge in water-fat imaging is robust separation of the water and fat components. In this work, we propose a method that performs a series of dual-echo reconstructions using different pairs of echoes. The estimates from the multiple reconstructions are then combined to generate a more robust initial estimate of the water and fat images. The final estimates are then calculated via voxel-wise minimization. The proposed multiple dual-echo method demonstrates an improvement to single dual-echo reconstruction for water-fat imaging. |
| 3231 | Multiparameter mapping of T2, R2*, fat fraction using a combination of chemical shift imaging and phase-based T2 mapping | |
| Daiki Tamada1, Xiaoke Wang1, Diego Hernando1,2, and Scott B. Reeder1,2,3,4,5 | ||
1Radiology, University of Wisconsin-Madison, Madison, WI, United States, 2Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 3Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States, 4Medicine, University of Wisconsin-Madison, Madison, WI, United States, 5Emergency Medicine, University of Wisconsin-Madison, Madison, WI, United States |
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A new multi-parameter method for quantitative mapping of T2, R2*, and fat fraction using CSE-MRI combined with phase-based T2 mapping was developed. This method can be performed using the RF phase-modulated gradient echo sequences that encode T2 information into the phase of the steady-state signal. A phantom study demonstrating the ability of this approach to obtain 3D high-resolution quantitative maps in reasonable acquisition time. |
| 3232 | A pulse sequence for robust and efficient quantitative R1rho asymmetry imaging to probe chemical exchange effect | |
| Baiyan Jiang1 and Weitian Chen1 | ||
1Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong, Hong Kong |
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The measurement of R1rho (1/T1rho) spectrum and its asymmetry have several advantages over Chemical Exchange Saturation Transfer (CEST) to probe chemical exchange effect. Previously reported AC-iTIP approach is able to obtain R1rho-spectrum and R1rho asymmetry robustly. However, it suffers from long scan time. In this work, we proposed a new AC-iTIP approach to reduce the scan time by approximately 30%~40%, without compromising the robustness. |
| 3233 | Single Current Diffusion Tensor Magnetic Resonance Electrical Impedance Tomography: A Simulation Study | |
| Mehdi Sadighi1, Mert Şişman1, Berk Can Açıkgöz1, and B. Murat Eyüboğlu1 | ||
1Electrical and Electronics Engineering Dept., Middle East Technical University (METU), Ankara, Turkey |
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Diffusion Tensor Magnetic Resonance Electrical Impedance Tomography (DT-MREIT) is an imaging technique providing low-frequency conductivity tensor images. In all DT-MREIT applications in the literature two linearly independent current injection patterns are used to reconstruct the extra-cellular conductivity and diffusivity ratio (ECDR) which is the space-dependent scale factor between the conductivity and diffusion tensors in a porous medium. In this study, a new approach is proposed to reconstruct ECDR using only one current injection pattern. The proposed method is evaluated using simulated measurements with different SNR levels. The obtained results show similar performance compared to the conventional two current DT-MREIT. |
| 3234 | High-Efficient Metabolic Nano-Theranostics for MR Imaging and Cancer Therapy | |
| Peng Wang1, Yaqiong Wang1, Jie Zhu2, Yong Zhang3, Ke-Xue Deng1, and Hui-Jun Dong1 | ||
1Radiology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, China, 2Electronic information engineering, University of Aeronautics and Astronautics, Nanjing, China, 3GE Healthcare, Shanghai, China |
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In order to realize the nanotheranostics and reduce the toxicity of nanotheranostics agents to healthy tissues/organs, we constructed a novel nanotheranostics agents (Gd-DTPA-CS@β-CD@Dox) for MR imaging and Cancer treatment. Renal-clearable nanocomposites made it possible to overcome the long-term toxicity by accumulation in healthy living body. High uptake of the as-synthesized Gd-DTPA-CS@β-CD@Dox was achieved due to the longer blood circulation time. Moreover, the nanotheranostics agents possessed excellent performance in MRI. The nanotheranostics agents demonstrated a PH sensitive drug release. Such functional nanotheranostics agents applicable in highly integrated bio-modal imaging and multiple therapeutic functions may have great prospects in clinical practice. |
| 3235 | 4D Flow for estimation of global and local pulse wave velocity in stenotic femoral arteries | |
| Ingo Hermann1,2, Martin Sigl3, Stefan Schönberg4, Lothar R. Schad1, and Frank G. Zöllner1 | ||
1Computer Assisted Clinical Medicine, Medical Faculty Mannheim, University Heidelberg, Mannheim, Germany, 2Magnetic Resonance Systems Lab, Department of Imaging Physics, Delft University of Technology, Delft, Netherlands, 3First Department of Medicine, Medical Faculty Mannheim, Mannheim, Germany, 4Institute of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim, Mannheim, Germany |
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Pulse wave velocity (PWV) is a promising biomarker for decreasing artery diameter and wall stiffness. Recent work showed the possibility to calculate the local PWV from the velocity profil time delay along the artery out of 4D Flow measurements. In this study we used 4 different models (half maximum, maximum, foot-to-foot, cross-correlation) to compare and calculate the PWV in the relatively small femoral arteries in five subjects with stenotic arteries. We found an increased PWV of up to 20 m/s compared to literature values of healthy volunteers. Cross-correlation and half maximum methods yielded consistent results. |
| 3236 | Parameter estimation with matrix-based signal models using VARPRO for transient- and steady-state imaging | |
| Nam Gyun Lee1 and Krishna S. Nayak2 | ||
1Biomedical Engineering, University of Southern California, Los Angeles, CA, United States, 2Electrical and Computer Engineering, University of Southern California, Los Angeles, CA, United States |
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VARPRO-based parameter estimation is extensively used in MR for its improved accuracy, precision, and convergence behavior compared to general nonlinear least-squares algorithms. This study investigates the feasibility of using matrix-based signal models with VARPRO instead of conventional analytic signal equations. Simulations and in-vivo study show that VARPRO with matrix-based signal models is identical to VARPRO with analytic signal equations, and both VARPRO approaches provide enhanced precision and accuracy in relaxometry maps compared to the conventional DESPOT1/2 methods from variable flip angle SPGR and bSSFP measurements. |
| 3237 | Simultaneous Quantification of SPIO and Gd contrast agents using MR Fingerprinting | |
| Anna Marriott1,2, Chris Bowen1,2, James Rioux1,2, and Kimberley Brewer1,2 | ||
1Biomedical Translational Imaging Centre (BIOTIC), HALIFAX, NS, Canada, 2Department of Physics & Atmospheric Science, Dalhousie University, HALIFAX, NS, Canada |
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Superparamagnetic Iron Oxide (SPIO) contrast agents are used extensively in molecular imaging studies as a tool to evaluate various SPIO-labelled cells. These studies would be greatly improved if multiple contrast agents could be quantified simultaneously. We combined an SSFP MR fingerprinting sequence with TE variation, and an extension of a concentration-dependent linear model, to achieve dual quantification and show viability of SPIO labelled CD8+ T cell mapping. As a pilot study for in vivo application, we demonstrate concentration mapping of a mouse injected with gadolinium, and R2* quantification of an SPIO labelled immune therapy injection site. |
| 3238
|
Vessel size imaging using hypoxia and hyperoxia gas challenges with spin- and gradient-echo (SAGE) MRI | |
| Chau Vu1, Jian Shen1, and John C. Wood1,2 | ||
1Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States, 2Departments of Pediatrics and Radiology, Children's Hospital Los Angeles, Los Angeles, CA, United States |
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This study demonstrated the feasibility of using hyperoxia and transient hypoxia gas challenges in conjunction with spin- and gradient-echo (SAGE) MRI to estimate vessel size index (VSI). Hypoxia yielded an average VSI of 14μm within acceptable range for healthy tissue, whereas hyperoxia severely underestimated vessel sizes. Test-retest in two patients demonstrated repeatability of hypoxia-VSI. Future work to optimize the acquisition and cross-validate against other VSI methodologies is required to assess the diagnostic value of this technique. |
| 3239 | In Vivo Myelin Quantification by T1w/T2w: Its Relationship with Other MRI Quantifiers of Myelin and Specificity | |
| Hiroyuki Hamaguchi1, Nina Patzke2, Yuta Urushibata3, Xinnan Li1, Isabel Fernandez2, and Khin Khin Tha4,5 | ||
1Department of Biomarker Imaging Science, Hokkaido University Graduate School of Biomedical Science and Engineering, Sapporo, Japan, 2Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan, 3Siemens Healthineers, Tokyo, Japan, 4Department of Diagnostic and Interventional Radiology, Hokkaido University Hospital, Sapporo, Japan, 5Global Station for Quantum Medical Science and Engineering, Hokkaido University, Sapporo, Japan |
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The division of T1-weighted image by T2-weighted image (T1w/T2w) has recently been introduced as a myelin quantifier, which gained attention due to the ease of obtaining images. However, controversy exists about its performance. The aim of this study was to test the correlation of T1w/T2w with other MRI quantifiers of myelin, so as to determine its performance. Moderate to strong correlation of T1w/T2w with the other quantifiers was observed. T1w/T2w appears to be sensitive to detect an abnormality, but is not specific for myelin. |
| 3240 | Accurate mapping of T2 relaxation times at low SNR, based on Bloch simulations and PCA image denoising | |
| Neta Stern1, Dvir Radunsky1, Tamar Blumenfeld-Katzir1, and Noam Ben-Eliezer1,2,3 | ||
1Bio-medical Engineering, Tel Aviv University, Tel Aviv, Israel, 2Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel, 3Center for Advanced Imaging Innovation and Research (CAI2R), New-York University Langone Medical Center, New York, NY, United States |
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Quantitative T2 mapping using Bloch simulations offers high mapping accuracy, albeit may suffer from reduced precision due to noisy data when operating at low SNR. In this work we tested the utility of PCA-based complex image denoising for increasing T2 mapping precision. Mapping was done using the echo modulation curve algorithm. Denoising was tested on phantom and in vivo scans. Comparing T2 maps before and after PCA complex image denoising showed an increase in T2 precision with no apparent loss of spatial resolution. |
| 3241 | Rapid and Direct Quantification of Gadolinium from Blood using Time Resolved Fluorescence | |
| James Tranos1, Ayesha Bharadwaj Das1, Zakia Ben Youss Gironda1, Nora Butler1, Jin Zhang1, Stewart Russell2, S. Gene Kim1, and Youssef Zaim Wadghiri1 | ||
1Bernard & Irene Schwartz Center for Biomedical Imaging (CBI), Department of Radiology and Center for Advanced Imaging Innovation and Research (CAI2R), New York University School of Medicine, New York, NY, United States, 2Institute for Ultrafast Spectroscopy and Lasers, The City College of New York, New York, NY, United States |
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There are increasing needs to quantify the concentration of gadolinium for use in pharmacokinetic modeling, and traditional MR techniques prove to be inadequate. As an alternative, Time Resolved Fluorescence (TRF) can be used to directly measure the concentration of gadolinium, using a GBCA conjugated to a fluorescent antenna moiety. Here we show that TRF serves as a sensitive and direct approach to quantify the concentration of a sensitized GBCA, as a bifunctional contrast agent. |
| 3242 | Magic Sandwich to Stimulated Echo Relative change to identify sign and intensity of dipolar interaction in anisotropic tissue | |
| Eloïse MOUGEL1, Hélène RATINEY1, Eric VAN REETH1,2, Kevin TSE VE KOON1, Olivier BEUF1, and Denis GRENIER1 | ||
1Univ Lyon, INSA‐Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, F‐69616, LYON, France, 2CPE, VILLEURBANNE, France |
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Among the MR techniques playing on dipolar interaction (Hd), the magic sandwich echo sequence (MSE) is very seldom used in biological application. So far, the magic echo has been compared to the spin echo. However, MSE is closer to a stimulated echo thus a Magic Sandwich to Stimulated echo relative change (MaSteR) is of interest to study. The MaSteR evolution with spin-lock intensity increase was studied for thawed tendon for different orientations within B0 to modulate the dipolar interaction. We show that MaSteR is correlated to dipolar interaction, sample composition and its evolution with orientation is sensitive to Hd sign. |
| 3243 | 3D-FLAIR imaging with optimized scan parameters to visualize endolymphatic hydrops with intravenous gadolinium-based contrast media | |
| Jinye Li1, Lixin Sun1, Long Li2, Hui Zhao1, Jing Tian1, Gesheng Song3, Na Hu1, Weiqiang Dou4, and Ruozhen Gong5 | ||
1Department of Radiology, Shandong Provincial ENT Hospital, Shandong Provincial ENT Hospital affiliated to Shandong University, Jinan, China, 2Department of Medical Service, Shandong Provincial ENT Hospital, Shandong Provincial ENT Hospital affiliated to Shandong University, Jinan, China, 3Shandong province Qianfoshan Hospital, Jinan, China, 4GE Healthcare, MR Research China, Beijing, China, 5Gong Ruozhen Innovation Studio, Shandong Medical Imaging Research Institute Affiliated to Shandong University, Jinan, China |
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We aimed to explore the optimal scan parameters of 3D-FLAIR technique in labyrinthine lymph imaging for patients with vertigo disease. With different scan times and scan baselines applied, the corresponding 3D-FLAIR images were systematically compared. We found that the optimal scan time was 6hours after intravenous administration of GBCM. Additionally, the optimal scan baseline, aiming to obtain the relative maximum areas of the saccule, utricle and lateral semicircular canal to be displayed at the same level, is about 10.74±2.24 degrees from the anterior skull base. Therefore, using these optimal parameters, an accurate determination of endolymphatic hydrops can be achieved. |
| 3244 | Biochemical Insights into the Molecular Mechanisms of Gadolinium Long-Term Deposition in the Human Body | |
| Patrick Werner1,2, Patrick Schuenke1, Matthias Taupitz3, and Leif Schröder1 | ||
1Leibniz-Forschungsinstitut fuer Molekulare Pharmakologie, Berlin, Germany, 2BIOphysical Quantitative Imaging Towards Clinical Diagnosis (BIOQIC), Berlin, Germany, 3Department of Radiology, Charite Berlin, Berlin, Germany |
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The biochemical and molecular mechanisms of the gadolinium long-term deposition in biological tissues are widely unknown. In this study we prove that the observed hyperintensity of divined regions in the human body after clinical GBCA intervention can be caused by macromolecular species like glycosaminoglycans. We are able to show the importantance of sulfate groups and the influence of the sulfation state of these endogenous polysaccharides for this process by using MR relaxometry and isothermal titration calorimetry (ITC). |
| 3245 | Macromolecular Pool Fraction (MPF) Maps in Minimal Scan Time Using a Modified Fast SPGR Sequence and a Calibrated Synthetic MT Reference Image | |
| Kim Desmond1, Tobias C Wood2, and Sofia Chavez1 | ||
1CAMH, Toronto, ON, Canada, 2King's College, London, United Kingdom |
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MPF has been shown to correlate with myelin. Recent advances have reduced the required acquisitions to two: with (MTΔ) and without (MT0) the MT pulse. These, along with B1 and T1 maps, can be used to compute MPF. Scan time can be minimized by synthesizing MT0 from the T1 and B1 maps required for MPF mapping thus obviating the need to acquire MT0. Here we present advances that allow for MPF mapping in a minimal scan time (about 10 min) . These include optimizing B1 and T1 mapping implementations with calibration procedures to ensure accuracy and modifying an accelerated MT-prepared sequence. |
| 3246 | Shearlet-based susceptibility map reconstruction with iterative reweighting and nonlinear data fitting | |
| Janis Stiegeler1,2 and Sina Straub1 | ||
1German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Faculty of Physics and Astronomy, Heidelberg University, Heidelberg, Germany |
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The QSM algorithms tested in the 2016 Reconstruction Challenge showed oversmoothing effects and a notable loss of details. A multicale shearlet system was used to reconstruct the susceptibility map. Iterative reweighting of the coefficients led to a sparse image in the shearlet space. The result shows that shearlets are useful to obtain quantitative susceptibility maps which are rich in detail and simultaneously can achieve a top ten result in the ranking of the 2016 Reconstruction Challenge. |
| 3247 | A low-cost, versatile phantom for elastography: validation via numerical simulations and MRE | |
| Maksym Yushchenko1, Mathieu Sarracanie1,2, Jens Wuerfel2,3, and Najat Salameh1 | ||
1Laboratory for Adaptable MRI Technology (AMT lab), Dpt of Biomedical Engineering, University of Basel, Allschwil, Switzerland, 2Medical Image Analysis Center (MIAC AG), Basel, Switzerland, 3Quantitative Bioimaging Group (qbig), Dpt of Biomedical Engineering, University of Basel, Allschwil, Switzerland |
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We describe the fabrication of a low-cost, silicone-based phantom for elastography, which provides precise geometries and controlled stiffness. Simulations were carried out to produce synthetic MRE data and verify the performance of MRE reconstruction in ideal conditions. To our knowledge, this is the first time that simulations can be validated on exact same physical objects, making this approach very handy to optimize acquisition parameters and establish reconstruction validity criteria of elastography data. Such phantoms can be prepared with different mechanical properties, and could thus be broadly used as an accessible mean to assess the robustness of MRE tools. |
| 3248 | Signatures of microstructure in R2* decay: defining the limits of the weak field approximation | |
| Pippa Storey1 and Dmitry S. Novikov1 | ||
1Department of Radiology, New York University School of Medicine, New York, NY, United States |
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R2* decay is nontrivial in the presence of magnetic microstructure; the logarithm of the signal is approximately quadratic over short times (the static dephasing regime) and asymptotically linear at long times (the diffusion narrowing regime). The transition can, in principle, provide an estimate of the characteristic length scales of the microstructure. Using Monte Carlo simulations of water molecules diffusing through a magnetic field perturbed by magnetic microstructure, we explore the regime of validity of the weak field approximation, in which the signal can be calculated analytically. We also illustrate how the signal behavior changes beyond the weak field limit. |
| 3249 | On the Saturation Scheme in Chemical Exchange Saturation Transfer Imaging with B0 Inhomogeneity | |
| Ruibin Liu1, Qiuping Ding1, Yi-Cheng Hsu2, Yi Sun2, Dan Wu1, and Yi Zhang1 | ||
1Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China, 2MR Collaboration, Siemens Healthcare Ltd., Shanghai, China |
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Saturation pulses are an indispensable part in Chemical Exchange Saturation Transfer (CEST) imaging. Different saturation schemes can be designed for CEST imaging, including the pulse shape, duration of each pulse element, number of pulse elements, inter-pulse spoiler gradient, and inter-pulse gap, etc. Here, the impact of saturation schemes subject to practical B0 inhomogeneity is investigated, using Bloch simulations, and phantom and human experiments. Specifically, it’s shown that Gaussian and rectangular saturation pulses demonstrate substantially different susceptibility to imaging artifacts in the presence of B0 inhomogeneity when changing the duration of each saturation pulse element, and the inter-pulse spoiler gradients. |
| 3250 | Reliability Study of Quantitative Susceptibility Mapping from Three-Dimensional Echo-Planar Imaging with 2 Minutes Scan Time | |
| Krishna Pandu Wicaksono1, Yasutaka Fushimi1, Tomohisa Okada2, Satoshi Nakajima1, Sonoko Oshima1, Yusuke Yokota1, Azusa Sakurama1, Sayo Otani1, and Kaori Togashi1 | ||
1Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, Kyoto, Japan, 2Human Brain Research Center, Kyoto University, Graduate School of Medicine, Kyoto, Japan |
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3D-EPI QSM has been proposed as one solution of QSM long scan time which hinders its routine application. As its validity has been ascertained in our phantom study, in-vivo reliability study is warranted. This healthy participant study demonstrated excellent reliability of 3D-EPI QSM with 2 minutes’ scan time, compared to the “standard” 5 minutes’ GRE QSM, favoring further study to evaluate its actual clinical performance. |
| 3251 | Renal Susceptibility Imaging: Analysis of Susceptibility Weighted Imaging and Quantitative Susceptibility Mapping in Transplanted Kidneys | |
| Hyun-Seo Ahn1, Hyo Sung Kwak2, and Sung-Hong Park1 | ||
1Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea, 2Department of Radiology, Bio medical Research Institute of Chonbuk National University Hospital, Jeonju, Republic of Korea |
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Renal susceptibility imaging is challenging due to the motion artifacts in kidney. In this study, susceptibility weighted imaging (SWI) and quantitative susceptibility mapping (QSM) were performed on transplanted kidney patients, who show less kidney motions. QSM images successfully demonstrated oxygen gradients in kidney, i.e., the hypoxic state in medulla and the fully oxygenated state in cortex. Heterogeneous susceptibility distributions were observed near medullary veins, presumably due to medullary hypoxia and incomplete local phase unwrapping. Further studies are necessary for more complete local phase unwrapping and quantification of oxygenation levels in medullary veins from QSM images. |
| 3252 | Quantitative susceptibility mapping with 1mm isotropic resolution in 2 minutes using compressed sensing | |
| Arun Joseph1,2,3, Tom Hilbert4,5,6, Gabriele Bonanno1,2,3, Emilie Mussard4,5,6, Christoph Forman7, Ashley Stewart8,9, Kieran O’Brien8, and Tobias Kober4,5,6 | ||
1Advanced Clinical Imaging Technology, Siemens Healthcare AG, Bern, Switzerland, 2Translational Imaging Center, Sitem-Insel, Bern, Switzerland, 3Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland, 4Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland, 5Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, 6LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland, 7Siemens Healthcare AG, Erlangen, Germany, 8Siemens Healthcare Pty Ltd, Brisbane, Australia, 9Queensland Brain Institute, The University of Queensland, Brisbane, Australia |
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Quantitative susceptibility mapping exploits magnetic susceptibility to probe biological tissue. The obtained quantitative information carries additional clinical value, e.g. for the diagnosis of neurodegenerative diseases. However, standard protocols have long acquisition times which impedes their use in clinical routine. Here, we propose a compressed sensing acquisition based on a Cartesian spiral-phyllotaxis readout scheme to drastically reduce the total acquisition times from 20 minutes to 2 minutes for a 1mm isotropic susceptibility map of the whole brain. A preliminary qualitative and quantitative validation is performed on healthy subjects. |
| 3253 | Identifying Different Types of Local Lesions in the Lenticular Nucleus of Patients with Wilson’s Disease using Quantitative Susceptibility Maps | |
| Gaiying Li1, Rong Wu2, Yasong Du3, Kelly M Gillen4, Yi Wang4, Xiaoping Wang2, and Jianqi Li1 | ||
1East China Normal University, Shanghai, China, 2Shanghai Tong-Ren Hospital, Shanghai, China, 3Shanghai Mental Health Center, Shanghai, China, 4Weill Medical College of Cornell University, New York, NY, United States |
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The objective of this study was to discriminate signal changes of edema, encephalomalacia and excessive metal deposition in the lenticular nucleus of patients with Wilson’s Disease on quantitative susceptibility maps. Standard T1- weighted, T2- weighted, T2 FLAIR and QSM images were obtained on 14 WD subjects using 3T MRI. The results indicated that QSM could effectively discriminate different types of local lesions, including metal deposition hyperintensity, encephalomalacia hypointensity, and edema medium intensity. Furthermore, our study revealed that UWDRS and neurological symptoms scores of patients with severe abnormal MRI manifestations were significantly higher than that of patients with mild abnormal MRI. |
| 3254 | Detection of Iron Deposition in Substantia Nigra for Mouse of Parkinson’s Disease: A Comparison of Quantitative Susceptibility Mapping and R2* | |
| Yihao Guo1,2, Jijing Guan1, Jinghui Xu3, Wenbin Si1, Yingjie Mei4, Qianjian Feng1,2, Yunqi Xu3, and Yanqiu Feng1,2 | ||
1School of Biomedical Engineering, Southern Medical University, Guagnzhou, China, 2Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guagnzhou, China, 3Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, China, 4Philips Healthcare, Guangzhou, China |
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Parkinson’s disease (PD), a common neurodegenerative disorder, is associated with iron deposition in the substantial nigra (SN) of both human and animal models. SN iron is a potential biomarker for diagnosing and monitoring PD. The aim of this study was to compare QSM and R2* for quantifying SN iron in mouse brain. |
| 3255 | Shielded Electromagnetic Transducer for Liver Magnetic Resonance Elastography | |
| Mohammad Honarvar1, Shahed Khan Mohammed1, Qi Zeng1, Caitlin Schneider1, Robert Rohling1, Piotr Kozlowski2,3, and Septimiu Salcudean1 | ||
1Electrical and Computer Engineering, University of British Columbia, Vancouver, BC, Canada, 2UBC MRI Research Center, Vancouver, BC, Canada, 3Department of Radiology, University of British Columbia, Vancouver, BC, Canada |
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Electromagnetic shielded Lorentz coil actuator allows using the magnetic field of the MRI scanner to induce arbitrary elastic waves in the tissue in a cost-effective way. We developed a Lorentz coil actuator for the liver magnetic resonance elastography (MRE) for providing a larger wave coverage area, where the Lorentz coil is placed outside the imaging area by the use of an additional end-effector. Initial testing for phantom showed an excellent agreement with the reported elasticity, while the liver elasticity study provided promising results in detecting cirrhosis and hepatitis C virus. |
| 3256 | Simulation study for investigating the reliability of susceptibility mapping for the superior sagittal sinus from single echo 3D GRE phase | |
| Soohyun Jeon1, Yoonho Nam2, Jinhee Jang3, and Dong-Hyun Kim1 | ||
1Department of Electrical & Electronic engineering, Yonsei University, Seoul, Korea, Republic of, 2Department of Radiology, The Catholic University of Korea, Seoul, Korea, Republic of, 3Radiology, The Catholic University of Korea, Seoul, Korea, Republic of |
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Quantitative Susceptibility Mapping (QSM) is a technique to describe local susceptibility distribution in the human body . Especially, QSM has the potentials to provide oxygen metabolic information of the venous structure in the brain such as dural sinuses. Among the group of this sinuses, the superior sagittal sinus (SSS) often have been investigated in, neurovascular researches such as Parkinson's disease, headache and stroke . However, the SSS of the susceptibility mapping are often eroded in the conventional QSM pipeline. In this study, we investigate the reliability of QSM for the SSS from single echo 3D GRE phase using the simulated phase data. |
| 3257 | QSM streaking suppression with L1 data fidelity terms | |
| Carlos Milovic1,2,3, Mathias Lambert1,2,3, Christian Langkammer4, Kristian Bredies5, Cristian Tejos1,2,3, and Pablo Irarrazaval1,2,3 | ||
1Department of Electrical Engineering, Pontificia Universidad Catolica de Chile, Santiago, Chile, 2Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, Chile, 3Millennium Nucleus for Cardiovascular Magnetic Resonance, Santiago, Chile, 4Department of Neurology, Medical University of Graz, Graz, Austria, 5Institute of Mathematics and Scientific Computing, University of Graz, Graz, Austria |
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L2-norm based data fidelity terms in QSM functionals account for Gaussian noise in the phase or complex domain. These approaches are not robust against phase inconsistencies, such as artifacts from previous steps, intra-voxel dephasing, etc. To deal with these errors and to suppress streaking artifacts we present L1-norm algorithms that correct for salt-and-pepper noise. We use simulations and in-vivo acquisitions to show their streaking suppression capabilities. Furthermore, L1 methods do not require magnitude information, and they were able to achieve similar results without ROI masks. This may facilitate susceptibility studies of cortical areas and regions outside the brain. |
| 3258 | Perfusion Estimates of Fast Dynamic Contrast Enhanced MRI Correlates with Dynamic Susceptibility Contrast in Brain Metastases Follow-up | |
| Benoit Bourassa-Moreau1, Réjean Lebel1, Ella Benzaquen2, Ismaël Labbé3, Guillaume Gilbert4, David Mathieu3, and Martin Lepage1 | ||
1Centre d’imagerie moléculaire de Sherbrooke, Département de médecine nucléaire et radiobiologie, Université de Sherbrooke, Sherbrooke, QC, Canada, 2Département radiobiologie diagnostique, Université de Sherbrooke, Sherbrooke, QC, Canada, 3Service de neurochirurgie, Département de chirurgie, Université de Sherbrooke, Sherbrooke, QC, Canada, 4MR Clinical Science, Philips Healthcare Canada, Markham, ON, Canada |
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Perfusion MRI is routinely used for brain tumor diagnosis and treatment follow-up. This work compares the performance of the standard dynamic susceptibility contrast sequence against a new fast dynamic contrast-enhanced sequence for brain metastasis follow-up after stereotactic radiosurgery. This new sequence enables the simultaneous measurement of blood brain barrier permeability that could help differentiate tumor recurrence and pseudo-progression. Our preliminary results show a correlation between relative cerebral blood volume estimates from both methods. A trend towards significance after analysis of thirteen lesions is expected to reach significance after inclusion of the remainder of our cohort. |
| 3259 | Influence of different temporal resolutions by varying parallel imaging factors on DCE perfusion parameters studied in a phantom | |
| Tanja Uhrig1, Frank Zöllner1, and Lothar Schad1 | ||
1Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany |
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No uniform consensus on the optimal sampling resolution for quantitative DCE MRI exists. In order to increase the sampling resolution, accelerated parallel imaging techniques (PAT) can be used. The inter- and intra-measurement precision of the plasma flow (PF) was determined in a phantom depending on the sampling resolution (1.9-3.8s), achieved by varying the PAT factor (1-6). A significant influence of the PAT factors and the sampling resolution on the PF itself and the robustness and reproducibility of the fit could be observed, even with small sampling rates as recommended in literature. |
| 3260 | A Novel Approach Using First-Pass Adjusted DTR-DCE-MRI (FAD) for Accurate Super-Spatial Resolution Brain Pharmacokinetic Parametric Mapping | |
| Xiaoping Zhu1, Daniel Lewis2, Sha Zhao1, Alan Jackson1, and Ka-Loh Li1 | ||
1DIIDS, University of Manchester, Manchester, United Kingdom, 2Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom |
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This study describes a new dual-injection, dual-temporal resolution (DTR) DCE-MRI mapping technique, which performs first-pass adjustment (FAD) of pre-bolus uptake curves using enhancement patterns measured from a main-dose, high-spatial resolution DCE acquisition. This new technique permits derivation of whole brain, super-spatial resolution kinetic parameter maps and its clinical applicability in vivo was assessed through application to retrospective DTR-DCE-MRI data from 12 NF2 patients undergoing Avastin therapy. Compared to the classical DTR-DCE-FDHS, method, baseline Ktrans derived using the FAD technique demonstrated superior ability in the prediction of 90 day volumetric response in Avastin treated NF2 related VS. |
| 3261 | Optimization of the Injection Protocol for Carotid Black-blood and Interleaved Black-bright-blood Dynamic Contrast-Enhanced MRI | |
| Yajie Wang1, Yishi Wang2, Xian Liu1, and Huijun Chen1 | ||
1Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing, China, 2Philips Healthcare, Beijing, China |
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The injection protocol used in carotid dynamic contrast-enhanced (DCE) MRI varies among different studies. The effect of the injection protocol on carotid black-blood and interleaved black-bright-blood DCE sequences were evaluated in this study. The results demonstrated that high injection dose (~ 0.1mmol/kg) with relative low effective injection rate (< 0.3mmol/s) was recommended for the simulated black-blood and interleaved black-bright-blood sequences. These two sequences were also shown to be insensitive to the uncertain time gap between the contrast injection and the post-contrast image acquisition. |
| 3262 | Range of Gd-DTPA concentration where $$$T_1$$$ shortening effect remains linear at 3T, 9.4T and 11.7T | |
| Anh Nguyen Tuan Tran1,2, Xing Qi Teo2, Septian Hartono1, Philip Teck Hock Lee2, Choon Hua Thng1, and Tong San Koh1 | ||
1Oncologic Imaging, National Cancer Center Singapore, Singapore, Singapore, 2Functional Metabolism Group, Singapore BioImaging Consortium, Singapore, Singapore |
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In $$$T_1$$$-weighted perfusion studies, the relationship between the contrast concentration and $$$T_1$$$ shortening effect is assumed to be linear within the clinical range. However, this assumption may not hold at higher concentration observed in the arterial input functions (AIFs). We set out to investigate this relationship by measuring the $$$R_1$$$ relaxation rate of various Gd-DTPA concentrations in saline. We find that the change in $$$R_1$$$ relaxation rate of Gd-DTPA is linear up to 4 mM at 9.4T and 11.7T, and up to 5 mM at 3T. At higher concentration, $$$R_1$$$ relaxation rate increases faster than a linear relationship. |
| 3263 | Use of arterial spin labeling MRI in differentiating fat-poor angiomyolipoma from clear cell renal cell carcinoma | |
| Qing Xu1, Weiqiang Dou2, and Jing Ye1 | ||
1Department of Radiology, Clinical Medical School of Yangzhou University, Northern Jiangsu People’s Hospital, Yangzhou, 457, China, 2GE Healthcare, MR Research China, Beijing, China |
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In this study, we aimed to test if arterial spin labeling (ASL) MRI can be used to differentiate renal fat-poor angiomyolipoma (AML) from the clear cell renal cell carcinoma (ccRCC). To achieve this goal, we compared the ASL derived parameters including tumor blood flow (TBF), tumor-to-cortex ratio, and tumor-to-medulla ratio between fat-poor AML and ccRCC. Our results showed that TBF, tumor-to-cortex and tumor-to-medulla ratios were notably higher in ccRCC group than in fat-poor AML group (270.49±78.88ml/100g/min vs. 146.68±47.21ml/100g/min, 1.22±0.26 vs. 0.74±0.14, 3.13±0.94 vs. 1.77±0.55; p<0.05), indicating that ASL MRI can be an effective tool in differentiating fat-poor AML from ccRCC. |
| 3264 | Optimization of Pseudo Continuous Arterial Spin Labeling for measuring perfusion in CKD patients | |
| Rebeca Echeverria-Chasco1, Marta Vidorreta2, Verónica Aramendia-Vidaurreta1, Nuria Garcia-Fernandez3, Gorka Bastarrika1, and Maria A. Fernandez-Seara1 | ||
1Radiology, Clinica Universidad de Navarra, Pamplona, Spain, 2Siemens Healthineers, Madrid, Spain, 3Nephrology, Clinica Universidad de Navarra, Pamplona, Spain |
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The main goal of this work was to optimize the robustness of pseudo continuous Arterial Spin Labeling (pCASL) to acquire renal images in CKD patients. The optimization was firstly carried out through numerical simulations, and a pCASL experiment in healhty volunteers to assess the veracity of the simulations. The results were in agreeement with the simulations (p-value = 0.04). For CKD patients, the numerical simulations were made to select the parameters that maximize the efficiency. The results for CKD patients and controls that show highest efficiencies are ratios 6-7 and Gave of 0.5-0.7 mT/m. |
| 3265 | Dynamic arterial spin labeling MRI of cerebrovascular perfusion during exercise | |
| Isa Mast1,2, Koen P.A. Baas2, Aart J. Nederveen2, and Adrianus J. Bakermans2 | ||
1Human Movement Sciences, Vrije Universiteit van Amsterdam, Amsterdam, Netherlands, 2Radiology and Nuclear Medicine, Amsterdam UMC, Amsterdam, Netherlands |
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Pathophysiological changes in cerebrovascular reactivity can remain undetectable at rest, and may only become apparent during a cerebrovascular challenge. We evaluated the feasibility of dynamically measuring the cerebrovascular response to exercise using pseudo-continuous arterial spin labeling (pCASL) at 3 Tesla during a bicycle exercise-recovery stress test. We observed a transient increase in cerebrovascular blood flow (CBF) during exercise in four volunteers, demonstrating that pCASL-MRI can capture dynamic changes in CBF during physiological bicycle exercise. This approach may become an important quantitative tool to noninvasively investigate the cerebrovascular reactivity in health and disease. |
| 3266 | Time Course of Cerebral Blood Flow in Patients with Symptomatic Middle Cerebral Artery Stenosis during Lipid-lowering Treatment | |
| Hualu Han1, Dandan Yang1, Huiyu Qiao1, Zihan Ning1, and Xihai Zhao1 | ||
1Tsinghua University, Beijing, China |
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Statin treatment is considered as an effective method to stabilize atherosclerosis and potentially improve cerebral perfusion. This study evaluated the changes of artery stenosis and CBF on arterial spin labeling during statin treatment with two-years’ follow-up. We found that CBF improved in the symptomatic territory among all subjects at 6th month (rCBF: 0.92±0.07 vs. 0.95±0.07, P=0.001). After 6 months, however, CBF decreased in patients with stenosis progression whereas maintained at a stable level in patients with stenosis regression, suggesting that changes of symptomatic MCA stenosis may have an effect on the cerebral hemodynamic improvements during statin treatment in different stages. |
| 3267 | ASL perfusion imaging predicts cognitive impairment in cerebral small vessel disease | |
| Joana Pinto1, Ana Fouto1, Rita G. Nunes1, Luísa Alves2, Sofia Calado2, Carina Gonçalves2, Margarida Rebolo3, Miguel Viana Baptista2, Pedro Vilela4, and Patrícia Figueiredo1 | ||
1ISR-Lisboa/LARSyS and Department of Bioengineering, Instituto Superior Técnico – Universidade de Lisboa, Lisboa, Portugal, 2Neurology Department, Hospital Egas Moniz, Centro Hospitalar de Lisboa Ocidental; CEDOC - Nova Medical School, New University of Lisbon, Lisboa, Portugal, 3Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal, 4Imaging Department, Hospital da Luz, Lisboa, Portugal |
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Cerebral small vessel disease (SVD) is one of the most common vascular causes of dementia, and a major contributor of age-related cognitive decline. We evaluated cerebral perfusion using arterial spin labeling (ASL), in terms of its predictive power of cognitive impairment in a group of SVD patients. We employed a multiple-delay pulsed ASL acquisition and fitted an extended kinetic model to the signal in order to derive cerebral blood flow (CBF) as well as bolus arrival time (BAT) maps. Regression analysis demonstrated that CBF in gray matter (GM) significantly contributed to explaining cognitive impairments in processing speed. |
| 3268 | Machine Learning to Improve Compatibility of Multi Centre Arterial Spin Labelling Data to Characterise Dementia Spatial Perfusion Abnormality | |
| Jack Highton1, Rebecca Steketee2, Rozanna Meijboom3, Marion Smits2, Ross Paterson4, Nick Fox4, Alexander Foulkes5, Catherine Slattery5, Jonathan Schott5, Enrico De Vita6, and David L Thomas7,8,9 | ||
1Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, 2Department of Radiology and Nuclear Medicine, Erasmus Medical Centre, Rotterdam, Netherlands, Rotterdam, Netherlands, 3Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom, 4Institute of Neurology, University College London, London, United Kingdom, 5Dementia Research Centre, University College London, London, United Kingdom, 6King's College London, London, United Kingdom, 7University College London, London, United Kingdom, 8Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, Institute of Neurology,, University College London, London, United Kingdom, 9Wellcome Centre for Human Neuroimaging, Institute of Neurology, University College London, London, United Kingdom |
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Arterial Spin Labelling (ASL) is a non-invasive MRI method to measure cerebral blood flow (CBF). Here, Support Vector Machine (SVM) based machine learning was used to identify spatial patterns of CBF abnormality in patients with Alzheimer’s Disease from two cohorts scanned at different centers. Support Vector Machine Regression models were found to be more accurate than conventional SVMs previously used for dementia classification. Then, motivated by the lack of ASL standardisation, an SVM based method was used to improve the compatibility of the two studies by removing differences in spatial patterns likely caused by differences in hardware and acquisition protocol. |
| 3269 | Untangling Perfusion from Atrophy in Fronto-Temporal Dementia using Multimodal Correlation and Machine Learning | |
| Jack Highton1, Rebecca Steketee2, Rozanna Meijboom3, Marion Smits2, Enrico De Vita4, Jonathan Schott5, and David L Thomas6,7,8 | ||
1Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, 2Department of Radiology and Nuclear Medicine, Erasmus Medical Centre, Rotterdam, Netherlands, Rotterdam, Netherlands, 3Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom, 4King's College London, London, United Kingdom, 5University College London, London, United Kingdom, 6Dementia Research Centre, University College London, London, United Kingdom, 7Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, Institute of Neurology, University College London, London, United Kingdom, 8Wellcome Centre for Human Neuroimaging, Institute of Neurology,, University College London, London, United Kingdom |
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Partial volume correction (PVC) is often applied to analyse cerebral blood flow (CBF) in dementia, in order to isolate perfusion changes from atrophy of grey matter. But PVC inevitably results in spatial smoothing of CBF, which may weaken the informative spatial pattern of CBF changes. Here, machine learning was used to detect Fronto-Temporal Dementia (FTD), considering spatial patterns in CBF from Arterial Spin Labelling, with and without PVC. Also, multimodal voxel concordance analysis untangled the spatial relationship between GM atrophy and CBF. This information was used with CBF PVC to improve the FTD detection accuracy without the atrophy signature. |
| 3270 | Time-encoded ASL provides added value in differentiating healthy older from younger individuals compared to single time-point methods | |
| Lena Vaclavu1, Carles Falcon 2, Paula Montesinos 3, Kim van de Ven4, Juan Domingo Gispert 2, and Matthias J.P. van Osch1 | ||
1Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, 2Pasqual Maragall Foundation, Barcelonaβeta Brain Research Center (BBRC), Barcelona, Spain, 3Philips Iberia, Madrid, Spain, 4Philips, Best, Netherlands |
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Age is an important risk factor for cerebrovascular disease. ASL can lend different insights depending on the choice of read-out (3D or 2D) and post-label-delay (PLD) for instance. We assessed differences in cerebral blood flow (CBF), and investigated the added value of arterial transit time (ATT) for differentiating older from younger healthy volunteers. Single-PLD 2D-pCASL and time-encoded (te-)ASL had almost identical CBF, while multi-PLD te-ASL offered the additional option to estimate ATT and blood volume. We found prolonged ATT despite unaffected CBF in older versus younger volunteers. TE-ASL could therefore provide ‘free’ information aside from perfusion in clinical settings. |
| 3271 | Arterial spin labeling signal in the Sagittal Sinus as hemodynamic proxy parameter in patients with sickle cell disease. | |
| Liza Afzali-Hashemi1, Lena Vaclavu2, Jan Petr3, John Wood4, Bart J Biemond5, Aart J Nederveen6, and Henk JMM Mutsaerts7 | ||
1Radiology and Nuclear Medicine, Amsterdam University Medical Center, location AMC, Amsterdam, Netherlands, 2Radiology, Leiden University Medical Center, Leiden, Netherlands, 3Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany, 4Department of Cardiology and Radiology, Children’s Hospital of Los Angeles, Los Angeles, CA, United States, 5Department of Hematology, Amsterdam UMC, location AMC, Amsterdam, Netherlands, 6Department of Radiology & Nuclear Medicine, Amsterdam UMC, location AMC, Amsterdam, Netherlands, 7Amsterdam UMC, Amsterdam, Netherlands |
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Higher sagittal sinus signal is present in the ASL images of patients with sickle cell disease (SCD). The purpose of this study was to assess if the signal in the sagittal sinus is correlated with clinical parameters and if this is affected by the vasoactive stimulus. The sagittal sinus signal was measured in patients with SCD and in healthy controls. Signal in sagittal sinus of the SCD patients were significantly correlated with clinical parameters including hemolysis markers. Our results show that sagittal sinus signal can be used as a hemodynamic proxy parameter in patients with SCD. |
| 3272 | DW-pCASL measure of BBB water permeability is sensitive to pharmacological manipulation of AQP4 function | |
| Hsiao-Ying Wey1, Xingfeng Shao2, and Danny JJ Wang2 | ||
1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States, 2USC Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, CA, United States |
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The blood-brain barrier (BBB) is a tightly regulated structure that protect the central nervous system (CNS). BBB impairment is implicated in several brain disorders, such as Alzheimer’s disease. Aquaporin-4 (AQP4) water channels are critically involved in regulating brain water transport across the BBB. We have recently developed a diffusion-weighted pCASL (DW-pCASL) technique allowing measurement of water permeability across the BBB. In this study, we implemented and optimized DW-pCASL in nonhuman primates. We directly validated that the underlying signal mechanism of DW-pCASL is related to AQP4-mediated BBB water exchange using a pharmacological challenge. |
| 3273 | Reliability and Reproducibility of ASL-MRI Measured Perfusion in GBM at 3T | |
| Limin Zhou1, Yiming Wang1, Marco Da Cunha Pinho1,2, Edward Pan3,4,5, Joseph Maldjian1,2, Yin Xi1,6, and Ananth Madhuranthakam1,2 | ||
1Radiology, University of Texas Southwestern Medical Center, Dallas, TX, United States, 2Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, 3Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, 4Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, TX, United States, 5Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, United States, 6Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, TX, United States |
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We have assessed the reliability of pCASL using 3D TSE-CASPR in healthy volunteers and glioblastoma (GBM) patients. “Excellent” agreement was observed for intrasession reliability in both normal appearing grey matter (NAGM) and tumors with intraclass correlation coefficient (ICC) of 0.945 (95% CI: 0.916-0.964) and 0.948 (95% CI: 0.883-0.978) respectively. Across multiple ROIs, the within-subject coefficient of variation (wsCV) was measured to be 6.1 ± 1.2% across all subjects in NAGM, and 5.1% in tumors. The lower wsCV in tumors allow 3D TSE pCASL using CASPR to be used for longitudinal monitoring of GBM patients. |
| 3274 | Reducing the effect of cerebrospinal fluid pulsation on arterial spin labeled perfusion MRI acquired with fast spin echo readouts | |
| Jianxun Qu1, Tianye Lin1,2, Karthik Prabhakaran3, M. Dylan Tisdall1, and John A. Detre1,3 | ||
1Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 2Chinese Academy of Medical Sciences, Peking Union Medical College, PUMCH, Beijing, China, 3Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States |
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Fast spin echo is widely used for ASL acquisition. However, if the flip angle reduced to minimize SAR and/or stabilize signal evolution over the echo train, the fluctuation of CSF increases markedly. This work explored the influence of minimum flip angle, and crusher strength in ASL acquisition. A CSF-prioritized background suppression (BS) planning was also performed. We found that increasing minimum flip angle together with reducing crusher in superior-inferior direction benefits the stability of ASL acquisitions. Prioritizing CSF suppression in BS was also helpful. |
| 3275 | Improved inflow saturation markedly reduces inflow artifacts in background-suppressed 3D arterial spin labeling | |
| Jianxun Qu1, Tianye Lin1,2, Priti Balchandani3, M. Dylan Tisdall1, and John A. Detre1,4 | ||
1Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 2Chinese Academy of Medical Sciences, Peking Union Medical College, PUMCH, Beijing, China, 3Icahn School of Medicine at Mount Sinai, New York, NY, United States, 4Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States |
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Inflow blood during the post labeling delay is a significant source of physiological noise in arterial spin labeling. This study utilized a novel inflow saturation method to address this issue. Compared to traditional inflow saturation approach where a 90o thick saturation slab is used to null blood within the interval of background suppression inversion pulses, the proposed method employs serial of thin slab sub-bolus saturations, with the saturation strength planned adaptively to return the blood to nulling point at the excitation point. The proposed method reduces the inflow artifacts markedly and mitigates global signal fluctuations. |
| 3276 | Off-resonance and flow-velocity immune ASL at low-power using pseudo-continuous saturation labeling | |
| Manuel Taso1 and David C. Alsop1 | ||
1Division of MRI research, Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States |
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While widely used for perfusion imaging, the flow-driven inversion labeling commonly used with pseudo-continuous ASL (PCASL) presents a significant off-resonance sensitivity as well as high power deposition potentially limiting high-field applications. We therefore investigated an alternate labeling scheme that takes advantage of the multiple aliased labeling planes that arise within the labeling RF envelope when reducing the peak-to-average gradient ratio. First numerical simulations and experiments show the potential for low-SAR, B0 and flow-velocity robust saturation labeling. |
| 3277 | Robust non-contrast pulmonary perfusion imaging using pseudo-continuous arterial spin labeling with background suppression | |
| Joshua S. Greer1,2, Yiming Wang2, Limin Zhou2, Tarique Hussain1,2, and Ananth J. Madhuranthakam2,3 | ||
1Pediatrics, UT Southwestern Medical Center, Dallas, TX, United States, 2Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 3Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States |
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Pulmonary perfusion imaging using ASL has been demonstrated using the pCASL technique with varying degrees of reproducibility. In this study, a pCASL labeling strategy is proposed to improve the stability of perfusion signal in the lungs using cardiac triggering to reduce flow-induced signal variations, and background suppression to improve SNR. With the proposed technique, high SNR perfusion images are created with a limited number of signal averages. This optimized approach may allow full coverage of the lungs in clinically reasonable scan times. |
| 3278 | High-resolution whole brain perfusion mapping in mice by a drift-corrected steady pulsed imaging and labeling sequence | |
| Wenjing Xu1,2, Jiadi Xu3,4, and Xiaoyong Zhang1,2 | ||
1Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China, 2Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence (Fudan University), Ministry of Education, Shanghai, China, 3Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 4F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States |
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We developed a drift-corrected steady pulsed imaging and labeling (dSPIL) to measure CBF with high-resolution and whole brain coverage. We applied a metric of low band pass to remove MRI signal drift using interleaved label-control images. We also optimized several key imaging parameters in an effort to minimize scan time while covering the whole brain. With the optimized dSPIL scheme, quantification of high-resolution CBF in 22 mouse brain regions can be obtained. As a demonstration and validation of the method, the volume of ischemic lesion regions in mice was quantified by calculating CBF reductions. |
| 3279 | Tagging Error Robust pseudo-Continuous Arterial Spin Labeling using Multiplane Labeling and Low Rank Methods | |
| Chenwei Tang1, Mu-Lan Jen1, Laura Eisenmenger2, and Kevin M Johnson1,2 | ||
1Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 2Department of Radiology, University of Wisconsin-Madison, Madison, WI, United States |
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While pseudo-continuous ASL (pCASL) is still the recommended technique for clinical and research applications, it suffers from subject vascular anatomy dependent variations in tagging efficiency which may lead to inaccurate quantification of perfusion, or gross misrepresentations of perfusion heterogeneity. In this work, we explore a strategy in which a span of tagging plane offsets and rotations is performed and cerebral blood flow (CBF) is robustly estimated retrospectively from the series of images with differential tagging efficiency. Our results demonstrate significant fluctuation of measured CBF for different relative labeling plane locations and robust recovered CBF against these fluctuations. |
| 3280 | Comparison of k-space filtering and variable flip angle schemes for reduced T2 blurring in 3D ASL MRI | |
| Yiming Wang1, Limin Zhou1, Sheng Qing Lin1, Joshua S. Greer1,2, and Ananth J. Madhuranthakam1,3 | ||
1Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 2Pediatrics, UT Southwestern Medical Center, Dallas, TX, United States, 3Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States |
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3D arterial spin labeled (ASL) MRI using turbo spin echo (TSE) based acquisitions suffer from image blurring, due to T2 decay along the echo train. To date, several methods have been proposed to reduce T2 blurring, including k-space filtering and variable flip angle schemes. In this study, the performances of k-space filtering was compared with variable flip angle scheme to compensate or reduce T2 blurring of 3D ASL images acquired with Cartesian TSE. Results showed k-space filtered images provided similar sharpness improvement compared with variable flip angle method. |
| 3281 | Variable Density Sampling of 3D TSE Cartesian Acquisition for Improved Robustness and SNR of ASL-MRI | |
| Yiming Wang1, Limin Zhou1, Joshua S. Greer1,2, Marco C. Pinho1,3, Joseph A. Maldjian1,3, and Ananth J. Madhuranthakam1,3 | ||
1Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 2Pediatrics, UT Southwestern Medical Center, Dallas, TX, United States, 3Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States |
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3D Cartesian turbo spin echo (TSE) acquisition has shown robustness for arterial spin labeled (ASL) MRI. However, 3D Cartesian TSE are acquired with single average due to relatively long TR and longer scan times, which may lead to suboptimal signal to noise ratio (SNR). In this study, we implemented variable density sampling of 3D Cartesian TSE that acquires the center of the k-space with higher signal averages, and improves the robustness and SNR without significantly prolonging the scan time. We further combined this with M0 images using partial k-space to compensate for increased scan time, but without compromising perfusion quantification. |
| 3282 | Optimal subject-specific pCASL settings by automated inner-scan timing adaption | |
| Nora-Josefin Breutigam1, Daniel Christopher Hoinkiss1, Mareike Alicja Buck1, Amnah Mahroo1, Federico von Samson-Himmelstjerna1, and Matthias Günther1,2 | ||
1MR Physics, Fraunhofer MEVIS, Bremen, Germany, 2MR-Imaging and Spectroscopy, Faculty 01 (Physics/Electrical Engineering, University of Bremen, Bremen, Germany |
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The presented automated inner-scan timing adjustment for subject-specific pCASL measurements can reduce uncertainties in perfusion quantification. The high variability of arterial transit times often leads to undesired arterial transit delay (ATD) artifacts. The method evaluated here allows the optimal FL-bolus duration to be individually adjusted by analyzing intermediate decoded perfusion-weighted images and directly adjusting the sub-bolus durations without increasing the measurement time. The aim is to reduce the FL-bolus duration as much as necessary, but to keep it as long as possible in order to obtain a maximum signal. |
| 3283 | Subject-specific background suppression in 3D pseudo-continuous arterial spin labeling perfusion imaging | |
| Jörn Huber1, Daniel Christopher Hoinkiss1, and Matthias Günther1,2 | ||
1Fraunhofer MEVIS, Bremen, Germany, 2University of Bremen, Bremen, Germany |
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This study introduces a subject-specific automated approach for optimization of background suppression (BS) in 3D pseudo-continuous arterial spin labeling perfusion imaging. Optimised timing of BS related FOCI pulses is calculated from the T1 spectrum, obtained from a M0 scan of the organ of interest. Results show strong suppression of brain tissue, when magnetization is nulled at the time of excitation as well as high quality perfusion images, when a slight delay between nullpoint and excitation is introduced for different numbers of FOCI pulses. |
| 3284 | Mitigating spurious transit time artifacts in background-suppressed multi-delay 3D pseudo-continuous ASL using inflow suppression | |
| Tianye Lin1,2, Jianxun Qu2, and John A. Detre2 | ||
1Chinese Academy of Medical Sciences, Peking Union Medical College, PUMCH, Beijing, China, 2University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States |
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The purpose of our study was to demonstrate that the inflow of arterial blood in post-labeling delay can cause intravascular high signal in multi-PLD ASL that resembles arterial transit artifact and potentially interfere with clinical interpretation. An optimized inflow-saturation method was used to suppress this artifact and improve the image quality of Hadamard-encoded and sequential multi-PLD ASL. |
| 3285 | Separating spin-compartment in arterial spin labeling using delays alternating with nutation for tailored excitation (DANTE) pulse | |
| Shota Ishida1, Hirohiko Kimura2, Naoyuki Takei3, Yasuhiro Fujiwara4, Tsuyoshi Matsuda5, Yuki Matta1, Masayuki Kanamoto1, Nobuyuki Kosaka2, and Eiji Kidoya1 | ||
1Radiological center, University of Fukui Hospital, Eiheiji, Japan, 2Department of Radiology, Faculty of Medical Sciences, University of Fukui, Eiheiji, Japan, 3Global MR Applications and Workflow, GE Healthcare Japan, Hino, Japan, 4Department of Medical Image Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan, 5Division of Ultra-high Field MRI, Institute for Biomedical Science, Iwate Medical University, Shiwa-gun, Japan |
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Delays alternating with nutation for tailored excitation (DANTE) pulse is capable of uniform and flow velocity related signal suppression. DANTE-ASL was compared to T2-mesurement in ASL (T2-ASL) to validate what spin-compartment is suppressed by DANTE. T2-ASL showed labeled signal remained in vascular compartment even at a PLD of 2.0 s. However, ASL signals using DANTE were approximately similar value in all the PLDs (0.5, 1.0, 2.0, and 3.0 s), because ASL signals in vascular compartment were suppressed selectively and sufficiently with concurrently preserving signals in tissue compartment. We could eliminate vascular compartment from total ASL signal using DANTE. |
| 3286 | Investigating the Repeatability of Cerebrovascular Reactivity Using Single and Multi-PLD PCASL | |
| Moss Y Zhao1, Audrey P Fan1, David Yen-Ting Chen1,2, David D Shin3, Mohammad Mehdi Khalighi1, Dawn Holley1, Kim Halbert1, Andrea Otte1, Brittney Williams1, Jun-Hyung Park1, Bin Shen1, and Greg Zaharchuk1 | ||
1Department of Radiology, Stanford University, Stanford, CA, United States, 2Department of Radiology, Shuang-Ho Hospital, Taipei Medical University, Taipei, Taiwan, 3GE Healthcare, Menlo Park, CA, United States |
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This work investigates the repeatability of CVR (induced by acetazolamide) using ASL on a healthy cohort. Single and multi-PLD PCASL data were collected before and after the administration of acetazolamide in two identical sessions. Results showed that the mean CVR of both ASL techniques were between 20% and 60% and not significantly different. Measurement using single-PLD PCASL demonstrated higher repeatability based on a lower coefficient of variation and a higher intraclass correlations. |
| 3287 | Examination of optimised PLD protocols for pCASL: accounting for dispersion and macrovascular contamination over a prolonged ATT range | |
| Xin Logan Zhang1, Joseph G. Woods1,2, Flora Kennedy McConnell1, Thomas W. Okell1, and Michael A. Chappell1 | ||
1Institute of Biomedical Engineering & Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom, 2Department of Radiology, University of California San Diego, La Jolla, CA, United States |
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A general framework has been proposed for optimising PLD sampling protocols in pCASL under an ideal kinetic model. In this study, the performance of CBF and ATT estimation of two optimised protocols CBF-ATTopt and CBFopt, along with a reference multi-PLD and single-PLD protocol, was investigated using simulations and in vivo when accounting for dispersion and macrovascular contamination (MVC) over a prolonged ATT range. CBFopt showed the least sensitivity among all protocols for CBF estimation when ATT was prolonged and when MVC was present. Future work can optimise for both macrovascular component and tissue component with a prolonged ATT range. |
| 3288 | Volumetric, multi B-value, multi-delay ASL using 3D single-shot spirals, expanded encoding models, and low rank reconstruction | |
| Mu-Lan Jen1, James H Holmes2, Laura Eisenmenger2, and Kevin M Johnson1,2 | ||
1Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 2Radiology, University of Wisconsin-Madison, Madison, WI, United States |
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In this work, we investigate a strategy to acquire single-shot, multi b-value, multi-delay ASL scans using the combination of an undersampled spiral in-out 3D fast spin echo readout with reconstructions enforcing a low rank constraint with an expanded encoding model. Images are demonstrated in healthy volunteers, acquiring single 3D ASL images in as short as 11s. |
| 3289 | Optimizing an Array-Compressed Coil for Arterial Spin Labeling at 7T | |
| Xinqiang Yan1,2, Manus J. Donahue1,2, and William A. Grissom1,2,3 | ||
1Department of Radiology, Vanderbilt University Medical Center, Nashville, TN, United States, 2Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, 3Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States |
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Arterial spin labeling (ASL) is a primary approach for non-invasive perfusion measurements with MRI. Theoretically, performing ASL at ultrahigh magnetic field strength can be beneficial because of the increased SNR as well as the lengthened T1-relaxation time. However, ASL is still not widely used at 7T due to the obstacles of B1+ inhomogeneity and high SAR associated with labeling. To overcome this problem, we apply array compressed parallel transmission (acpTx) in ASL and find that the optimized coil achieved 2x better B1+ homogeneity, and 4x lower SAR than a conventional 8-channel coil, which could enable 7T ASL with neck labeling. |
| 3290 | Robust Perfusion Parameter Quantification from 3D Single-Shot Multi-Delay ASL measurements | |
| Oliver Maier1, Stefan M Spann1, Daniela Pinter2, Thomas Gattringer2, Lukas Pirpamer2, Christian Enzinger2, Josef Pfeuffer3, and Rudolf Stollberger1,4 | ||
1Institute of Medical Engineering, Graz University of Technology, Graz, Austria, 2Deptartment of General Neurology, Medical University of Graz, Graz, Austria, 3Application Development, Siemens Healthcare, Erlangen, Germany, 4Biotechmed, Graz, Austria |
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Multi-Delay single-shot ASL imaging provides accurate CBF and, in addition, ATT maps but the inherent low SNR can be challenging. State-of-the-art fitting techniques can improve the SNR in the estimated maps but typically suffer from spatial blurring. To this end, we propose a new reconstruction method with a joint TGV regularization on CBF and ATT to reconstruct sharp maps with improved noise suppression. Validation of the proposed method on a healthy subject and five stroke patients showed preservation of even small features in CBF and ATT while increasing SNR and sharpness over recent approaches. |
| 3291 | Numerical Approximation to the General Kinetic Model for ASL Quantification | |
| Nam Gyun Lee1, Ahsan Javed2, Terrence R. Jao1, and Krishna S. Nayak2 | ||
1Biomedical Engineering, University of Southern California, Los Angeles, CA, United States, 2Electrical and Computer Engineering, University of Southern California, Los Angeles, CA, United States |
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We propose a numerical approximation to Buxton's general kinetic model (GKM) for ASL quantification that will enable greater flexibility in ASL acquisition methods. The proposed method combines the Bloch-McConnell equations with the flow effects and hence model the effects of flow simultaneously with magnetization transfer, T2 effects, off-resonance, and irregular timing of labeling. These can be solved using Jaynes’ matrix formalism. The proposed approximation is compared with GKM using simulations for PASL, PCASL, steady-pulse ASL, and MR fingerprinting ASL. Accuracy of the approximation is studied as a function of a key “time interval” parameter using Monte-Carlo simulations. |
| 3292 | Partial volume effect correction of arterial spin labelling data using surface segmentations | |
| Thomas Kirk1,2, Flora Kennedy McConnell1,2, Dimo Ivanov3, Sriranga Kashyap3, Martin Craig1,2, and Michael Chappell1,2 | ||
1Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom, 2Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom, 3Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands |
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We have recently developed a new approach to partial volume estimation that uses surface segmentations (for example, those produced by FreeSurfer). We compare this approach to conventional volumetric PV estimation for the application of PV correction to two ASL datasets and find evidence in support of using surface-derived PV estimates. |
| 3293 | Super-resolution reconstruction of single-PLD pseudo-continuous ASL images | |
| Piet Bladt1, Quinten Beirinckx1, Merlijn C.E. van der Plas2, Sophie Schmid2, Wouter M Teeuwisse2, Ben Jeurissen1, Arnold J den Dekker1, Jan Sijbers1, and Matthias J.P. van Osch2,3 | ||
1imec - Vision Lab, Department of Physics, University of Antwerp, Antwerp, Belgium, 2C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, 3Leiden Institute of Brain and Cognition, Leiden University, Leiden, Netherlands |
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Super-resolution reconstruction (SRR) allows for high-resolution image reconstruction from a set of low-resolution multi-slice images with different orientations. Arterial spin labeling (ASL) is an interesting albeit complicated candidate for SRR, as it relies on subtraction. SRR-ASL can be performed on low-SNR subtracted or on low-contrast unsubtracted ASL data. Different ASL-SRR implementations were applied to single-PLD PCASL data and validated against traditional ASL-scans. Combining motion correction, super-resolution post-processing and pairwise subtraction of label-control pairs in a single framework yielded comparable CBF maps as with traditional HR-ASL. Furthermore, in certain slices, SRR-ASL appears to reconstruct the underlying anatomical structure with higher fidelity. |
| 3294 | Measurement of intra- and extra-neurite perfusion by combining ASL with the NODDI DWI model | |
| Iris Asllani1,2, Alicia Plaindoux3, Jan Petr4, Joseph G. Woods5,6, Matthias J. P. van Osch7, and Mara Cercignani1 | ||
1Neuroscience, University of Sussex, Brighton, United Kingdom, 2Biomedical Engineering, Rochester Institute of Technology, Rochester, NY, United States, 3Grenoble Institute of Technology, Grenoble, France, 4Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany, 5University of California San Diego, San Diego, CA, United States, 6University of Oxford, Oxford, United Kingdom, 7Leiden University Medical Center, Leiden, Netherlands |
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Intra- and extra-neurite perfusion in gray and white matter were estimated by applying a spatial linear regression algorithm on ASL images using the micro-structural anatomical information derived from the NODDI analysis of the DWI data. Baseline ASL images were acquired with 4 post-labeling delay (PLD) values in order to test the hypothesis of redistribution of ASL signal across the micro-compartments with increasing PLD. Motor activation was used to investigate the sensitivity of the method for detecting changes in perfusion at the micro-structural level. |
| 3295 | Perfusion Quantification from Multi-delay Arterial Spin Labeling (ASL): Validation on Numerical Ground Truth | |
| Qihao Zhang1, Liangdong Zhou2, John Morgan3, Thanh D Nguyen4, Pascal Spincemaille3, and Yi Wang2 | ||
1Cornell University, Ithaca, NY, NY, United States, 2Weill Cornell Medicine, New York, NY, United States, 3Radiology, Weill Cornell Medicine, New York, NY, United States, 4Weill Cornell Medicine College, New York, NY, United States |
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Tissue flow vector field is generated by solving the inverse problem of a voxelized transport equation using multi-delay ASL data and an optimization method. The accuracy of the flow estimation is validated on a vasculature model. For calculating flow vector field in vivo, time resolved 3D (4D) tracer concentration data is acquired using a multi-delay pseudo continuous ASL sequence. The background suppression pulse is interleaved into labeling pulse to generate short post label delay. The output flow magnitude map shows a more anterior-poster-uniform CBF than the traditional Kety’s method. |
| 3296 | Low-Rank Reconstruction for Multi-Delay Arterial Spin Labeling | |
| Paul Kyu Han1, Yanis Djebra1,2, Thibault Marin1, Georges El Fakhri1, Jinsong Ouyang1, and Chao Ma1 | ||
1Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States, 2LTCI, Télécom Paris, Institut Polytechnique de Paris, Palaiseau, France |
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Multi-delay arterial spin labeling (ASL) is a powerful MRI technique that allows to non-invasively measure both cerebral blood flow and arterial transit time quantitatively, which has great potential for clinical applications. However, usage of multi-delay ASL is limited by the prolonged scan time with the number of post-labeling delay times used for acquisition. Up to date, low-rank property has been observed in signals of various MR applications where low-rank approach has demonstrated promising results. This work shows that the dynamics of ASL signal display low-rank property and the scan time of multi-delay ASL can be accelerated using low-rank image reconstruction. |
| 3297 | Estimation of cortical perfusion from arterial spin labelling data on the cortical surface | |
| Flora A. Kennedy McConnell1,2, Jack Toner1, Thomas Kirk1,2, Martin Craig1,2, Andrew R. Segerdahl2, Michael P. Harms3, and Michael A. Chappell1,2 | ||
1Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom, 2Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom, 3Department of Psychiatry, School of Medicine, Washington University, St Louis, MO, United States |
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Surface-based analysis is a popular approach to fMRI analysis as, compared with volumetric analysis, it allows easier registration of functional regions between individuals. This work sought to move towards surface-based perfusion analysis of arterial spin labelling data. It presents a comparison of the results of a surface-based analysis pipeline with results from a conventional volumetric perfusion analysis pipeline projected onto the cortical surface. Bayesian inference of cortical surface perfusion is demonstrated here and is shown to produce substantially lower perfusion estimates than conventional voxelwise analysis. Future work will investigate to origins of these perfusion differences. |
| 3298 | Use of population-derived perfusion information in predicting subject-specific perfusion references based on tissue partial volumes | |
| Flora Kennedy McConnell1,2, Sana Suri2,3, Eniko Zsoldos2,3, Klaus Ebmeier3, Clare MacKay2,3, and Michael Chappell1,2 | ||
1Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom, 2Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, United Kingdom, 3Department of Psychiatry, University of Oxford, Oxford, United Kingdom |
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Within and between subject variability in ASL perfusion data can obscure subtle perfusion changes indicative of neurodegenerative disease. It prohibits the production of a 'healthy' population-average perfusion atlas to which individuals can be compared. This work used a GLM to produce subject-specific perfusion references based on tissue partial volumes. Results show that such a linear model can successfully decompose perfusion, at the population level, into components related to tissue partial volumes. However, the model struggles to capture variability at the individual subject level and thus, the problem will in future be addressed with non-linear modelling techniques. |
| 3299 | A Learning-From-Noise Dilated Wide Activation Network for Denoising Arterial Spin Labeling (ASL) Perfusion Images | |
| Danfeng Xie1, Yiran Li1, Hanlu Yang1, Li Bai1, and Ze Wang2 | ||
1Temple University, Philadelphia, PA, United States, 2University of Maryland School of Medicine, Philadelphia, MD, United States |
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In this study, we showed that without a noise-free reference, Deep Learning based ASL denoising network can produce cerebral blood flow images with higher signal-to-noise-ratio (SNR) than the reference. In this learning-from-noise training scheme, cerebral blood flow images with very high noise level can be used as reference during network training. This will remove any deliberate pre-processing step for getting the quasi-noise-free reference when training deep learning neural networks. Experimental results this learning-from-noise training scheme preserved the genuine cerebral blood flow information of individual subjects while suppressed noise. |
| 3300 | Free Breathing Renal Perfusion Imaging at 3T Using Velocity-Selective Inversion prepared Arterial Spin Labeling | |
| Dan Zhu1,2, Dapeng Liu2,3, Wenbo Li2,3, Michael Schär2, and Qin Qin2,3 | ||
1Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 3. F.M. Kirby Research Center for Functional Brain Imaging, Johns Hopkins University School of Medicine, Baltimore, MD, United States |
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Renal perfusion has clinical significance in diagnosis of renal diseases. Velocity-selective arterial spin labeling (VSASL) has minimal sensitivity to arterial transit time delay and velocity-selective inversion (VSI) labeling could improve SNR of perfusion signal. Here renal VSASL images were acquired using different post-labeling delay time and under different B1 shimming conditions. The feasibility of VSI based ASL for renal perfusion mapping at 3T under free breathing is demonstrated on healthy volunteers. |
| 3301 | Improving Robustness to Field Imperfections for Velocity-Selective Inversion prepared Arterial Spin Labeling through Dynamic Phase-Cycling | |
| Dapeng Liu1,2, Wenbo Li1,2, Feng Xu1,2, Dan Zhu3, Taehoon Shin4,5, and Qin Qin1,2 | ||
1Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, 3Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 4Division of Mechanical and Biomedical Engineering, Ewha Womans University, Seoul, Korea, Republic of, 5Department of Medicine, Case Western Reserve University, Cleveland, OH, United States |
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In Fourier-transform based velocity-selective inversion (FT-VSI) arterial spin labeling (ASL), either velocity-insensitive or velocity-compensated waveforms could be applied for control modules. Under poor B0/B1 conditions with inefficient refocusing, the scheme with velocity-insensitive control is susceptible to strong false signal but maintained high labeling efficiency, while the scheme with velocity-compensated control has poor velocity-selective labeling profiles. This study overcome these problems by proposing a dynamic phase-cycling scheme based on velocity-insensitive waveform and improve the robustness to B0/B1 field inhomogeneities for VSI ASL. Simulation, phantom and brain ASL scans were conducted for demonstration. |
| 3302 | Comparison of 2D EPI and 3D multi-echo spin echo EPI readout for Venous Velocity Selective Inversion to measure venous blood T2. | |
| Sophie Schmid1,2, Leonie Petitclerc1,2, André Paschoal3, Suzanne Franklin1,4, Merlijn Van der Plas1,2, and Matthias Van Osch1,2 | ||
1Radiology, Leiden University Medical Center, Leiden, Netherlands, 2Leiden Institute of Brain and Cognition (LIBC), Leiden, Netherlands, 3Physics, InBrain Lab, University of Sao Paulo, Ribeirao Preto, Brazil, 4University Medical Center Utrecht, Center for Image Sciences, Utrecht, Netherlands |
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In this study the variation in the measured apparent T2 was assessed over different slices for venous velocity selective inversion (vVSI) with 2D EPI readout in the sagittal sinus and we compared vVSI with 2D EPI and 3D multi-echo spin echo EPI (mTE-SE-EPI) readout to the gold standard TRUST. With the 2D EPI readout the T2 increases significantly over the slices. |
| 3303 | Comparison of Velocity-Selective Arterial Spin Labeling using multiple VS Saturation and FT-VS inversion – a Theoretical Study | |
| Shaurov Das1, Luis Hernandez-Garcia2, Ryan Daniel Hernandez3, and Jia Guo1 | ||
1Bioengineering, University of California, Riverside, Riverside, CA, United States, 2Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States, 3Physics, University of California, Riverside, Riverside, CA, United States |
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Velocity selective ASL (VSASL) is the latest addition to the family of ASL techniques, with good promise on resolving transit delay sensitivity in ASL. Though an improvement in SNR efficiency has been reported by using two-module VS saturation and VS inversion pulse, the comparison between them is yet to be done. This study aims to compare their theoretical performance with Bloch simulation and a few realistic scenarios and look for knowledge about existing limitations which can, in turn, lead to further improvement of these techniques. Additionally, a few variants of VSI pulses including most recent improvement were explored and compared. |
| 3304 | Velocity selective arterial spin labeling at 7Tesla: a comparison of the temporal bolus width with FAIR | |
| Juliet Polkey1, Lydiane Hirschler2, Suzanne Franklin2, Matthias van Osch2, and Sophie Schmid2 | ||
1University College London Hospital, London, United Kingdom, 2Leiden University Medical Center, Leiden, Netherlands |
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To the best of our knowledge this work is the first implementation of VSASL at 7T. The VSASL technique was compared with FAIR in 3 healthy volunteers. The temporal bolus width was sampled in each case and compared between the two ASL methods. |
| 3305 | Experimental comparison of velocity selective ASL schemes | |
| Luis Hernandez-Garcia1 and Jia Guo2 | ||
1FMRI Laboratory, University of Michigan, Ann Arbor, MI, United States, 2University of California at Riverside, Riverside, CA, United States |
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This work presents an experimental comparison of different velocity selective (VS) labeling strategies for non-contrast perfusion MRI, including new variants of VS saturation and VS inversion, in relation to pseudo-continuous labeling pulses (PCASL). |
| 3306 | Implementation of Liver MR Elastography Tutorial Module to Improve Exam Quality and Reduce Patient Callback Rate | |
| Kelly Tung Smith1, Alvin Silva1, Jonathan Flug1, Justin Yu1, and Anshuman Panda1 | ||
1Radiology, Mayo Clinic Arizona, PHOENIX, AZ, United States |
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In this age of specialized imaging sequences such as liver MR elastography, inexperience with the technical image acquisition and unawareness of artifacts and pitfalls confound diagnostic accuracy due to poor image quality. We feel there is a knowledge gap in those at the front line involved with image acquisition, and that by defining and filling in this knowledge gap with an educational tutorial module, MR elastography image quality can be optimized and callback rates can be decreased. In turn, decreased callbacks will translate into reduced cost for unnecessary repeated scans; reduced patient time and frustration; and increased MR scheduling access. |
| 3307 | Optimal RF-Spoiling for Bias-Free Displacement Field Estimation in Fast 3D MR Elastography Sequences | |
| Christian Guenthner1 and Sebastian Kozerke1 | ||
1University and ETH Zurich, Zurich, Switzerland |
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RF-spoiling is employed in order to reduce transverse coherences. While spoiling angles are typically optimized for contrast, efficacy for bias-free phase-contrast measurements is yet to be proven. Here, we investigate the influence of the RF-spoiling angle on displacement estimates in fast GRE-MR Elastography sequences using Extended Phase Graph simulations. Theoretical findings are validated using a novel RF-spoiling test sequence as well as conventional MRE phantom experiments. An optimal spoiling angle of 158° degrees is identified allowing for bias-free MRE acquisitions at repetition times as low as 5ms. |
| 3308 | Simultaneous acquisition of multi-phase offset for rapid imaging in MR elastography (SAMURAI-MRE) using a multi-echo sequence | |
| Daiki Ito1,2,3, Tomokazu Numano1,3, Tetsushi Habe1,2, Toshiki Maeno1, Kazuyuki Mizuhara3,4, Surendra Maharjan1, Kouichi Takamoto5, and Hisao Nishijo6 | ||
1Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan, 2Office of Radiation Technology, Keio University Hospital, Tokyo, Japan, 3Health Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan, 4Department of Mechanical Engineering, Tokyo Denki University, Tokyo, Japan, 5Department of sport and Health Sciences, Faculty of Human Sciences, University of East Asia, Yamaguchi, Japan, 6System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan |
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MR elastography (MRE) requires acquisitions of multiple phase offset images. Patient movement between acquisitions of phase offset images is not only difficult to be detected, but also leads to calculate shear modulus incorrectly. To resolve this problem, we present a novel MRE technique that can acquire multiple phase offset images simultaneously (SAMURAI-MRE) using a motion-encoding gradient (MEG)-less multi-echo sequence. MRE images obtained at spin-echo (SE)- and gradient-echo (GRE)-based SAMURAI-MRE were compared with those at conventional SE- and GRE-based MEG-less multi-echo MRE. The results demonstrate that it is possible to perform SAMURAI-MRE, and SE-based SAMURAI-MRE was superior to GRE-based SAMURAI-MRE. |
| 3309 | Simultaneous Fat-Water MR Elastography Imaging using Distortion-free DIADEM-EPI | |
| Yi Sui1, MyungHo In1, Armando Manduca2, Matthew A. Bernstein1, Richard L. Ehman1, John III Huston1, and Ziying Yin1 | ||
1Radiology, Mayo Clinic, Rochester, MN, United States, 2Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States |
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Simultaneous fat-water EPI-MR elastography imaging was developed for acquisition of the brain (water) and skull (bone marrow fat) MRE motion. Compared to our previous dual-saturation and dual-sensitivity motion encoding (DSDM) technique, the proposed method minimize the EPI distortion and misalignment between skull and brain. This technique could offer a unique opportunity to quantify the skull-brain mechanical decoupling performance modulated by the pia-arachnoid complex, and its potential alterations in response to repetitive head impacts (RHI) in our future studies. |
| 3310 | Joint Elasticity Reconstruction and Displacement Filtering for 3D Magnetic Resonance Elastography | |
| Shahed Khan Mohammed1, Mohammad Honarvar1, Davood Karimi1, Piotr Kozlowski2,3, and Septimiu Salcudean1 | ||
1Electrical and Computer Engineering, University of British Columbia, Vancouver, BC, Canada, 2UBC MRI Research Center, Vancouver, BC, Canada, 3Department of Radiology, University of British Columbia, Vancouver, BC, Canada |
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Iterative reconstruction methods in magnetic resonance elastography (MRE) inversion can allow incorporating sparsity prior and can provide displacement filtering. However the problem is difficult to converge as MRE inversion is a non-convex and ill-conditioned problem. Here, we presented 3D ERBA with total variation prior on the elasticity, which showed good convergence by utilizing a bi-convex optimization of 3D finite element modeling of elastic wave. Extensive experiments on numerical phantom, agar phantom, and in-vivo liver study showed promising indications in detecting inclusion and abnormality, and improving the diagnostic efficacy of MRE. |
| 3311 | Dynamic MR elastography using MR magnitude images | |
| Tomokazu Numano1,2, Daiki Ito2,3,4, Kazuyuki Mizuhara5, Toshikatsu Washio2, Tetsushi Habe3,4, Toshiki Maeno3, Masaki Misawa2, and Naotaka Nitta2 | ||
1Radiological Sciences, Tokyo Metropolitan University, Tokyo, Japan, 2National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan, 3Tokyo Metropolitan University, Tokyo, Japan, 4Keio University Hospital, Tokyo, Japan, 5Tokyo Denki University, Tokyo, Japan |
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We developed a new technique for dynamic MR elastography (MRE) using a MR magnitude image. A general MRE uses a MR phase image as a wave image. Proposed technique was used a MR magnitude image instead of MR phase image as a wave image by using a special vibration. Proposed technique (special vibration MRE) performance was comparable to that of a continuous vibration MRE. Since special vibration MRE need an only few second vibration, it could dramatically eliminated the patients' vibration-related discomfort. |
| 3312 | Improving the SNR and Correcting the Bias in Elastograms in Helmholtz Inversion for MR Elastography | |
| Cemre Ariyurek1,2, Yusuf Ziya Ider1, and Ergin Atalar1,2 | ||
1Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey, 2National Magnetic Resonance Research Center (UMRAM), Ankara, Turkey |
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In Helmholtz inversion an equation is obtained for each MR elastography displacement data collected for each motion direction and each excitation frequency. Under high SNR, SNR of the estimated elasticity map by the Helmholtz inversion can be derived. Prior to the inversion, each equation can be weighted by the SNR of the elasticity estimate to improve SNR of the elastogram and low SNR ones can be thresholded to reduce bias in the elasticity estimation. Simulation and experiment results demonstrate that the original inversion underestimates the elasticity when there is noise and this bias can be corrected by the proposed reconstruction. |
| 3313 | Comparison of multi-platform 2D and 3D MR elastography in vivo and in vitro | |
| Paul Kennedy1,2, Daniel Stocker1,2, Octavia Bane1,2, Stefanie Hectors1,2,3, Bradley D Bolster Jr. 4, and Bachir Taouli1,2 | ||
1BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States, 2Department of Diagnostic, Molecular and Interventional Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States, 3Department of Radiology, Weill Cornell Medicine, New York, NY, United States, 4Siemens Medical Solutions USA, Inc., Salt Lake City, UT, United States |
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In this study we assess the variation in 2D and 3D MR elastography (MRE) measures in patients, volunteers and a phantom across two MR system vendors. Interobserver variability was also examined. 2D and 3D MRE liver measurements were not significantly different across systems and showed excellent intraclass correlation coefficient (ICC) between readers. Spleen measurement showed excellent ICC between readers but significant variation in 3D MRE spleen stiffness was found between systems. Liver 3D MRE is stable across platforms however further study is required to assess the bias in 3D MRE spleen measurements from multiple vendors. |
| 3314 | Noninvasive identification of renal perfusion in renal fibrosis of Adriamycin nephropathy by using ASL and IVIM-DWI imaging | |
| Shudan Min1, Jilei Zhang2, and Shenghong Ju1 | ||
1Jiangsu Key Laboratory of Molecular Imaging and Functional Imaging,, Southeast University, Nanjing, Jiangsu, China, 2Clinical Science, Philips Healthcare, Shanghai, China |
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Renal fibrosis is the final common consequence of chronic kidney disease (CKD) and is the mechanism of CKD progressing to end-stage renal failure. Here we employed ASL and IVIM to assess longitudinal changes of kidney perfusion to reflect renal fibrosis in an animal model of ADR nephropathy. A significant decline in renal microcirculation was detected in the ADR group compared with the sham group. Administration of VCP979 could prevent the renal perfusion, and the treatment response was also detected by the two imaging technology. |
| 3315 | Quantification of collateral blood flow using intravoxel incoherent motion MRI in a canine large vessel occlusion model of slow and fast evolvers | |
| Mohammed Salman Shazeeb1,2,3, Robert King1,2, Karl Helmer3, Josephine Kolstad1, Christopher Raskett1, Natacha Le Moan4, Jonathan A. Winger4, Lauren Kelly4, Ana Krtolica4, Nils Henninger1, and Matthew Gounis1 | ||
1University of Massachusetts Medical School, Worcester, MA, United States, 2Worcester Polytechnic Institute, Worcester, MA, United States, 3Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States, 4Omniox Inc., San Carlos, CA, United States |
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In acute ischemic stroke due to large vessel occlusion (LVO), variability of infarct evolution observed in humans is closely captured by the canine LVO model, which can predict dogs to be slow or fast evolvers. The extent of collateral blood supply has shown good correlations with infarct growth rate. This study investigated the use of intravoxel incoherent motion (IVIM) MRI to quantify microvascular perfusion. Longitudinal IVIM parameters clearly differentiated between slow and fast evolvers depicting collateral blood flow changes, which can determine the severity of ischemic injury and also track longitudinal changes in response to therapeutic treatments/interventions in preclinical studies. |
| 3316 | Blood flow MRI of the mouse optic nerve head | |
| Eric R. Muir1 and Timothy Q. Duong1 | ||
1Radiology, Stony Brook University, Stony Brook, NY, United States |
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Different retinal diseases likely affect the retinal, choroidal, and optic nerve head (ONH) circulations differently. Methods to quantitatively measure ONH blood flow with depth resolution are lacking. In this study, a blood flow MRI method was optimized to image blood flow of the ONH, retina, and choroid in the mouse eye at 42x42x275µm. This method could be useful to study models of retinal disease, such as glaucoma. |
| 3317 | Impaired blood flow and vascular reactivity in the choroid in diabetic mice | |
| Eric R. Muir1, Saurav B. Chandra2, Divya Narayanan3, Nikolay P. Akimov4, René C. Rentería4,5, and Timothy Q. Duong1 | ||
1Radiology, Stony Brook University, Stony Brook, NY, United States, 2Icon Clinical Research Inc, North Wales, PA, United States, 3Ora Clinical, Andover, MA, United States, 4Ophthalmology, University of Texas Health Science Center, San Antonio, TX, United States, 5School of Osteopathic Medicine, University of the Incarnate Word, San Antonio, TX, United States |
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Diabetic retinopathy is a microvascular disease of the retina, in which basal blood flow and the vascular responses to metabolic conditions in diabetic eyes are perturbed. To determine if diabetic mice have impaired retinal/choroidal blood flow and vascular reactivity, we measured ocular blood flow using MRI during hypercapnia. In diabetic mice, basal choroidal blood flow was significantly decreased. In both control and diabetic mice, hypercapnia caused a significant increase in retinal and choroidal blood flow, but the choroidal response was significantly reduced in diabetic mice, indicating impaired vascular reactivity. |
| 3318 | Parametric maps of murine cancers from dynamic contrast enhanced MRI: low versus high doses of contrast agent | |
| Xiaobing Fan1, Xueyan Zhou2, Devkumar Mustafi1, Federico Pineda1, Erica Markiewicz1, Marta Zamora1, Deepa Sheth1, Olufunmilayo I. Olopade3, and Gregory S. Karczmar1 | ||
1Radiology, The University of Chicago, Chicago, IL, United States, 2School of Technology, Harbin University, Harbin, China, 3Medicine, The University of Chicago, Chicago, IL, United States |
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We compared dynamic contrast enhanced (DCE) MRI with low (0.04mmol/kg) and high doses (0.2mmol/kg) of contrast agent on C3H mice at 9.4T with 1.5s temporal resolution before and after a bolus injection. The standard Tofts model was used to extract physiological parameters (Ktrans and ve) with arterial input function derived from muscle reference tissue. On average, rate constants were larger for low dose than high dose data. There were strong correlations for Ktrans and ve between low and high dose data. Therefore, low dose may be as effective as a high dose of contrast agent for cancer diagnosis. |
| 3319 | Parameters From Dynamic Contrast-Enhanced MRI Are Biomarkers Predicting Response after Radiotherapy to Brain Metastases | |
| Zhuo Shi1, Lizhi Xie2, Peng Wang1, Xinming Zhao1, and Han Ouyang1 | ||
1National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences, Beijing, China, 2GE Healthcare, MR Research China, Beijing, Beijing, China |
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Dynamic contrast-enhanced (DCE) MRI provides additional information on blood-brain barrier integrity. The Ktrans is a measure of capillary permeability obtained using DCE MRI that is directly proportional to the level of permeability of the blood-brain barrier. The purpose of this study was to evaluate the effect of SRS on cerebral metastases using Ktrans derived from DCE MRI and to explore the ability of Ktrans measurements on predicting midterm tumor outcomes after Stereotactic radiosurgery (SRS). |
| 3320 | Reducing TSM by Oxygen Inhalation: effective for pleural effusion but not ascites | |
| Xiaoqian Jia1, Jianxin Guo2, Xiaocheng Wei3, and Jian Yang2 | ||
1Ridiology, The First Affiliated Hospital of Xi'an Jiao Tong University, xi'an, China, 2The First Affiliated Hospital of Xi'an Jiao Tong University, xi'an, China, 3MR Research China, GE Healthcare, xi'an, China |
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In this study, we try to provide a wider cohort of subjects with continuous low flow oxygen inhalation during dynamic contrast-enhancedMR liver imaging to reduce “Transient Severe Motion” (TSM) after administration of gadoxetate disodium.In addition, separate comparison of arterial phase motion scores was conducted among: category of combined Pleural Effusion, category of combined Ascites, and category of None.The results show that continuous oxygen can significantly reduce the occurrence of TSM; and 1) pleural effusion may reduce image quality, and can be alleviated by oxygen inhalation, and 2) oxygen inhalation is less effective under the condition of ascites. |
| 3321 | Compartmental Low-Rank Denoising for Multi-Delay ASL | |
| Yanis Djebra1,2, Thibault Marin1, Jinsong Ouyang1, Georges El Fakhri1, Chao Ma1, and Paul Kyu Han1 | ||
1Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States, 2LTCI, Télécom Paris, Institut Polytechnique de Paris, Palaiseau, France |
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Arterial spin labeling (ASL) is a powerful magnetic resonance imaging (MRI) technique that allows to measure tissue perfusion, potentially an important biomarker for assessing cerebral tissue viability, without the use of contrast agent. However, the main drawback of ASL is in the intrinsically low signal-to-noise ratio (SNR). In this work, we investigate the low-rank property of ASL signal and explore the feasibility of improving the SNR of ASL signal using low-rank denoising approach. Results show that the ASL signal indeed display low-rank property and that the SNR in multi-delay ASL imaging can be improved using compartmental low-rank denoising method. |
| 3322 | Mechanical Property Recovery in the Cerebral Cortex using Magnetic Resonance Elastography | |
| Lucy V Hiscox1, Matthew DJ McGarry2, and Curtis L Johnson1 | ||
1University of Delaware, Newark, DE, United States, 2Dartmouth College, Hanover, NH, United States |
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Magnetic resonance elastography of the brain has shown promise as a sensitive neuroimaging biomarker for neurodegenerative disorders; however, the feasibility and reliability of performing MRE of the cerebral cortex warrants investigation due to the unique challenges of studying thinner and more complex geometries. In this work, we found good agreement between realistic simulated MRE data versus recovered displacement data of an older adult participant at various levels of applied Gaussian noise. Future work should consider additional and more advanced imaging and inversion approaches to improve the reliability and sensitivity of cortical MRE measures. |
| 3323 | Robustness of MR Elastography in the brain – Test-retest reliability and effect of different reconstruction methods | |
| Siri Flogstad Svensson1, Jorunn Fraser-Green2, Omar Darwish3, José Rodriguez de Arcos3, Tryggve Holck Storås1, Sverre Holm4, Ralph Sinkus3,5, and Kyrre Eeg Emblem1 | ||
1Department for Diagnostic Physics, Oslo University hospital, Oslo, Norway, 2The Intervention Center, Oslo University hospital, Oslo, Norway, 3Division of Imaging Sciences & Biomedical Engineering, King's College, London, United Kingdom, 4Department of Informatics, University of Oslo, Oslo, Norway, 5INSERM U1148, LVTS, University Paris Diderot, Paris, France |
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We assessed the test-retest reliability of MR Elastography, and compared the estimates of the shear storage modulus G’ (tissue elasticity) from two different reconstruction methods; a localized divergence-free finite-element approach and a local curl approach. The median coefficient of variation for two scans of the brain was 2.8 %, whereas the intraclass correlation coefficient between scan 1 and scan 2 was 0.80. G’ values estimated using the local curl method were 19% lower than with the divergence-free method. MRE of the human brain appears robust, while absolute values are dependent on the reconstruction method and should be used with care. |
| 3324 | Ultra-low frequency MR elastography of the in vivo human brain from endogenous pulsation to 40 Hz time-harmonic vibrations. | |
| Helge Herthum1, Heiko Tzschätzsch1, Felix Schrank1, Mehrgan Shahryari1, Gergely Bertalan1, Carsten Warmuth1, Jürgen Braun2, and Ingolf Sack1 | ||
1Department of Radiology, Charité Universitätsmedizin Berlin, Berlin, Germany, 2Institute of Medical Informatics, Charité Universitätsmedizin Berlin, Berlin, Germany |
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In this work, we applied single-shot steady-state MR elastography with spiral readout for quantifying shear wave speed (SWS) from endogenous pulsation to 40 Hz external vibrations with high sampling rate for first-time measurement of SWS dispersion of in vivo human brain in the ultra-low frequency regime. Ground truth SWS was determined by profile fitting approaches and reproduced by SWS mapping based on frequency-adaptive multi-component wave-number inversion. The obtained SWS dispersion was fitted by two-parameter viscoelastic models showing that brain tissue is dominated by fluid properties in this ultra-low frequency regime. Our method is potentially sensitive to vessel-related neurological disorders. |
| 3325 | Development of in vivo human brain DTI-MRE | |
| Shujun Lin1, Brad Sutton2, Richard Magin1, and Dieter Klatt1 | ||
1Richard and Loan Hill Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, United States, 2Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana-Champaign, IL, United States |
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Simultaneous acquisition of diffusion tensor imaging (DTI) and magnetic resonance elastography (MRE) has been proven feasible in previous pre-clinical studies. DTI-MRE requires the identification of experimental parameter ranges that depend on the specific target. Here we identify valid experimental parameter sets in simulations for in vivo human brain applications and the DTI-MRE technique is implemented by modifying a single-shot spin-echo EPI sequence. A good agreement was found between DTI-MRE and conventional acquisitions. DTI-MRE may increase the clinical acceptance of MRE and DTI by providing co-registered diffusion and tissue mechanical property maps within the scan time of a conventional DTI acquisition. |
| 3326 | The Investigation of Three-Dimensional MR elastography of the Brain in Multiple Sclerosis | |
| Ling Fang1, Matthew C. Murphy2, Sujuan Liu1, Qiuxia Luo1, Jingbiao Chen1, Bingjun He1, Wei Qiu3, Jun Chen2, Meng Yin2, Kevin J. Glaser2, Richard L. Ehman2, and Jin Wang1 | ||
1Department of Radiology, the Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China, 2Department of Radiology, Mayo Clinic, Rochester, MN, United States, 3Department of Neurology, the Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China |
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Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. MR Elastography (MRE) can quantitatively measure biomechanical tissue properties in vivo noninvasively. In this study, we investigated the potential value of MRE for the evaluation of centrum ovale viscoelasticity (including shear stiffness, storage modulus, shear loss modulus, and damping ratio) in Southern Chinese MS patients and to try to analyze its relevance to clinical manifestations. Our results showed that only the damping ratio of the centrum ovale was significantly decreased in MS patients and may provide a potential quantitative biomarker to evaluate MS. |
| 3327 | Free Breathing Magnetic Resonance Elastography in Patients with Idiopathic Pulmonary Fibrosis | |
| Faisal S Fakhouri1,2, Vincent Esguerra3, and Arunark Kolipaka1,2 | ||
1Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States, 2Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States, 3Division of Pulmonary, Critical Care, and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States |
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Interstitial lung diseases alter the mechanical properties of the lung parenchyma. Lung stiffness is a potential diagnostic marker. Standard breath hold techniques are difficult for patient with pulmonary disease. By using a free breathing Spin-Echo Dual-Density Spiral (SE-DDS) MRE sequence, a feasibility study was performed on 6 idiopathic pulmonary fibrosis (IPF) patients. It was found that the shear stiffness of IPF diseased lung is 2±0.48kPa for the right lung and 1.99±0.42kPa for the left lung which is significantly higher (P=0.0108 and P=0.0072) than healthy lungs, which has shear stiffness of 1.29±0.35kPa and 1.43±0.16kPa for right and left lungs, respectively. |
| 3328 | Helmholtz Inversion using Unconstrained Optimization for MR Elastography of the Lung: A Comparison to Direct Inversion | |
| Huiming Dong1,2, Rizwan Ahmad2, and Arunark Kolipaka1,2 | ||
1Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States, 2Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States |
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Lung stiffness is a potential biomarker for multiple lung diseases. MR elastography (MRE) allows non-invasive measurement of lung stiffness. However, it is challenging to estimate stiffness using direct Helmholtz inversion due to low signal-to-noise ratio (SNR) from lung MRE. In this work, a compressed-sensing-based Helmholtz inversion is proposed where noise is reduced via Laplacian of Gaussian (LoG) and Morozov’s discrepancy principle, while the sparsity of stiffness map is explored in a wavelet domain. Results demonstrated that the proposed inversion yielded robust stiffness estimation and successfully detected higher stiffness at total lung capacity (TLC) compared to residual volume (RV). |
| 3329 | In Vivo Aortic MR Elastography using Free-Breathing and Single-Breath-Hold SE-EPI: Inter-Scanner Reproducibility at 1.5T and 3T | |
| Huiming Dong1,2, Richard D White1,3, and Arunark Kolipaka1,2,3 | ||
1Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States, 2Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States, 3Internal Medicine-Division of Cardiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States |
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In vivo MR elastography (MRE) allows non-invasive estimation of aortic stiffness. Recently, the feasibility of multi-slice free-breathing (FB) spin-echo echo-planar imaging (SE-EPI) aortic MRE was investigated. In this study, a single breath-hold (SBH) SE-EPI aortic MRE protocol was proposed and compared to FB SE-EPI aortic MRE. Moreover, in vivo FB and SBH SE-EPI aortic MRE were studied using both1.5T and 3T scanners. The main aim was to assess inter-scanner reproducibilities of FB and SBH SE-EPI aortic MRE. |
| 3330 | Magnetic Resonance Elastography and Computational Modeling of Indeterminate Pulmonary Nodules Mechanical Properties. | |
| Faisal S Fakhouri1,2, Youjin Cho1,3, Joshua Englert4, Samir Ghadiali1,4, and Arunark Kolipaka1,2 | ||
1Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States, 2Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States, 3College of Medicine, The Ohio State University, Columbus, OH, United States, 4Division of Pulmonary, Critical Care, and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States |
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Many pulmonary diseases alter lung mechanical properties making lung stiffness an important biomarker. By using a Spin-Echo Echo Planar Imaging (SE-EPI) MRE sequence, a feasibility study was performed on 6 indeterminate pulmonary nodules (IPN) patients to determine the shear stiffness within the nodule and compare it with stiffness in the contralateral lung. It was found that in all the patients the median shear stiffness within the IPN was significantly higher than in the contralateral lung (1.77kPa vs 0.86kPa, p=0.008) Computational models based on MRE stiffness measurements also indicate decreased strain and increased strain gradients within the IPN. |
| 3331 | In Vivo Cardiac MR Elastography using Simultaneous Multi Slice Imaging | |
| Ayse Sila Dokumaci1, Torben Schneider2, Daniel Fovargue1, Anthony Price1, Omar Darwish1, George Jolly1, Stefan-Heinz Hoelzl1, Jelizaveta Sudakova1, Ralph Sinkus1,3, and David Nordsletten1,4 | ||
1Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom, 2Philips Healthcare, Guildford, United Kingdom, 3Inserm U1148, University Paris, Paris, France, 4Departments of Biomedical Engineering and Cardiac Surgery, University of Michigan, Ann Arbor, Ann Arbor, United Kingdom |
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MR Elastography is a technique to evaluate the biomechanical properties of soft tissues noninvasively. Its application in the heart is very challenging due to several factors including actuator hardware, robust MR sequences, and suitable reconstruction strategies. One of the biggest limitations for data acquisition of cardiac MRE scans is the breath hold duration which is up to 21 heart beats, repeated several times for a full dataset. The main goal of this study was the implementation of an MR sequence with simultaneous multi slice acquisition capability to reduce the breath hold duration and increase comfort and compliance for the subjects. |
| 3332 | Actuator-Free MR Elastography of the Liver: Imaging Liver Tumors with Viscoelastic Intrinsic MRE | |
| Elijah Van Houten1, Guillaume Gilbert2, and An Tang3 | ||
1Génie mécanique, Université de Sherbrooke, Sherbrooke, QC, Canada, 2MR Clinical Science, Philips Healthcare, Markham, ON, Canada, 3Département de radiologie, Université de Montréal, Montréal, QC, Canada |
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A new intrinsic activation MR Elastography method is presented through a proof of concept for imaging the viscoelasticity of a liver tumor. Results are presented for a healthy volunteer and a focal nodular hyperplasia subject. Relative stiffness, damping and compressibility maps clearly indicate the location of the tumor and are in agreement with mechanical property values previously reported in the literature. The method shows promise for the diagnosis of focal liver lesions and provides insight into new physiologically related biomarkers for these lesions. |
| 3333 | High-resolution multifrequency MR Elastography of liver tumors using a compact tabletop MRI Scanner | |
| Mehrgan Shahryari1, Gergely Bertalan1, Helge Herthum1, Heiko Tzschätzsch1, Jürgen Braun2, Marcus R. Makowski1, Sarah Keller1, and Ingolf Sack1 | ||
1Department of Radiology, Berlin, Germany, 2Institute of Medical Informatics, Berlin, Germany |
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MR elastography is a clinical imaging technique for the mapping of viscoelastic tissue properties on the millimeter scale. However, basic studies in tissue samples require a compact MRE setup which provides sub-millimeter resolution. We here introduce compact 0.5-Tesla tabletop multifrequency MRE for high-resolution mapping of viscoelasticity and water diffusion in VX2-liver tumors and surrounding liver tissue. Ex-vivo tumors were stiffer, more viscous and showed higher water diffusivity than adjacent tissue. In tumors, viscosity was inversely correlated with water diffusion while in liver tissue, stiffness was inversely correlated with diffusion. |
| 3334 | Validation of the Accuracy of Magnetic Resonance Elastography of the Liver via 3D Finite Element Modelling Simulation | |
| Deirdre McGrath1,2, Christopher Bradley1,2, and Susan Francis1,2 | ||
1NIHR Nottingham Biomedical Research Centre, Radiological Sciences, Division of Clinical Neuroscience, Queens Medical Centre, Nottingham, United Kingdom, 2Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom |
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In this novel study, magnetic resonance elastography (MRE) of the liver is simulated in a detailed 3D anthropomorphic finite element model of the human torso, to explore the influence of imaging spatial resolution and motion-based signal to noise ratio (SNR) on the accuracy of elastograms calculated by direct inversion. It was found that MRE accuracy was highly dependent on imaging voxel dimensions, motion-SNR and the ground truth material properties. These findings will guide the optimisation and development of future liver MRE methodology. |
| 3335 | Tomoelastography for Quantification of Heterogeneity in Primary Sclerosing Cholangitis-related Hepatic Fibrosis | |
| Rolf Reiter1,2, Heiko Tzschätzsch1, Matthias Haas1, Christian Bayerl1, Dieter Klatt2, Meltem Uyanik2, Shreyan Majumdar2, Marion Muche3, Bernd Hamm1, Jürgen Braun4, Ingolf Sack1, and Patrick Asbach1 | ||
1Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 2Bioengineering, University of Illinois at Chicago, Chicago, IL, United States, 3Hepatology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 4Medical Informatics, Charité - Universitätsmedizin Berlin, Berlin, Germany |
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Primary sclerosing cholangitis (PSC) is a rare chronic liver disease that leads to stricturing of bile ducts and a heterogeneous distribution of hepatic fibrosis. Despite the success of MR cholangiopancreaticogram and liver biopsy for the detection of PSC, they do not correlate with the severity of disease. Currently, there is no accurate diagnostic reference standard for monitoring the disease activity in PSC which limits patient management. Tomoelastography has the potential to quantify heterogeneity in PSC-related hepatic fibrosis using a normalized standard deviation index as a new biomarker besides overall stiffness. |
| 3336 | Feasibility of Tomoelastography in Inflammatory Bowel Disease: Preliminary Results | |
| Rolf Reiter1, Florian Nino Loch2, Carsten Kamphues2, Stephan Rodrigo Marticorena Garcia1, Bernd Hamm1, Jürgen Braun3, Ingolf Sack1, and Patrick Asbach1 | ||
1Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 2Surgery, Charité – Universitätsmedizin Berlin, Berlin, Germany, 3Medical Informatics, Charité - Universitätsmedizin Berlin, Berlin, Germany |
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Despite its success in the detection of inflammatory bowel disease (IBD), standard clinical MRI and other imaging modalities do not correlate with disease severity and cannot differentiate fibrotic and inflammatory bowel strictures. Anatomical details such as the descending colon and other parts of the intestine were demarcated on tomoelastography stiffness and fluidity maps, even without superimposed morphological images. Preliminary results demonstrate the feasibility of investigating IBD using tomoelastography. This study motivates larger trials and the assessment of fibrosis and inflammation in active IBD. |
| 3337 | Evaluation of precision of the psoas major muscle MR elastography | |
| Tetsushi Habe1,2, Tomokazu Numano1,3, Daiki Ito1,2,3, Toshiki Maeno1, Kazuyuki Mizuhara4, Kouichi Takamoto5, and Hisao Nishijo6 | ||
1Department of Radiological Sciences, Tokyo Metropolitan University, Tokyo, Japan, 2Office of Radiation Technology, Keio University Hospital, Tokyo, Japan, 3Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki, Japan, 4Department of Mechanical Engineering, Tokyo Denki University, Tokyo, Japan, 5Department of Sport and Health Sciences, University of Ease Asia, Yamaguchi, Japan, 6Department of System Emotional Science, Toyama University, Toyama, Japan |
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We developed psoas major muscle (PM) MR elastography (MRE) technique and reported shear modulus of the PM for the first time in the world. However, measurement precision (repeatability and reproducibility) of this technique was not assessed. In this study, repeatability with three repetitions and reproducibility with different three operators were evaluated. Repeatability of this technique was about the same as required for clinical liver MRE and reproducibility was almost perfect. The original vibration pad was focused on generating shear wave in the PM efficiently. The development of the vibration pad specialized for PM MRE resulted in acceptable repeatability and reproducibility. |